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* Merge branch 'sched-core-for-linus' of ↵Linus Torvalds2012-05-226-608/+352
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler changes from Ingo Molnar: "The biggest change is the cleanup/simplification of the load-balancer: instead of the current practice of architectures twiddling scheduler internal data structures and providing the scheduler domains in colorfully inconsistent ways, we now have generic scheduler code in kernel/sched/core.c:sched_init_numa() that looks at the architecture's node_distance() parameters and (while not fully trusting it) deducts a NUMA topology from it. This inevitably changes balancing behavior - hopefully for the better. There are various smaller optimizations, cleanups and fixlets as well" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched: Taint kernel with TAINT_WARN after sleep-in-atomic bug sched: Remove stale power aware scheduling remnants and dysfunctional knobs sched/debug: Fix printing large integers on 32-bit platforms sched/fair: Improve the ->group_imb logic sched/nohz: Fix rq->cpu_load[] calculations sched/numa: Don't scale the imbalance sched/fair: Revert sched-domain iteration breakage sched/x86: Rewrite set_cpu_sibling_map() sched/numa: Fix the new NUMA topology bits sched/numa: Rewrite the CONFIG_NUMA sched domain support sched/fair: Propagate 'struct lb_env' usage into find_busiest_group sched/fair: Add some serialization to the sched_domain load-balance walk sched/fair: Let minimally loaded cpu balance the group sched: Change rq->nr_running to unsigned int x86/numa: Check for nonsensical topologies on real hw as well x86/numa: Hard partition cpu topology masks on node boundaries x86/numa: Allow specifying node_distance() for numa=fake x86/sched: Make mwait_usable() heed to "idle=" kernel parameters properly sched: Update documentation and comments sched_rt: Avoid unnecessary dequeue and enqueue of pushable tasks in set_cpus_allowed_rt()
| * sched: Taint kernel with TAINT_WARN after sleep-in-atomic bugKonstantin Khlebnikov2012-05-181-0/+1
| | | | | | | | | | | | | | | | | | | | Usually sleep-in-atomic bugs are followed by dozens other warnings. This patch should help to figure out original source of problem. Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20120510122004.4873.12726.stgit@zurg Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * sched: Remove stale power aware scheduling remnants and dysfunctional knobsPeter Zijlstra2012-05-172-367/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It's been broken forever (i.e. it's not scheduling in a power aware fashion), as reported by Suresh and others sending patches, and nobody cares enough to fix it properly ... so remove it to make space free for something better. There's various problems with the code as it stands today, first and foremost the user interface which is bound to topology levels and has multiple values per level. This results in a state explosion which the administrator or distro needs to master and almost nobody does. Furthermore large configuration state spaces aren't good, it means the thing doesn't just work right because it's either under so many impossibe to meet constraints, or even if there's an achievable state workloads have to be aware of it precisely and can never meet it for dynamic workloads. So pushing this kind of decision to user-space was a bad idea even with a single knob - it's exponentially worse with knobs on every node of the topology. There is a proposal to replace the user interface with a single 3 state knob: sched_balance_policy := { performance, power, auto } where 'auto' would be the preferred default which looks at things like Battery/AC mode and possible cpufreq state or whatever the hw exposes to show us power use expectations - but there's been no progress on it in the past many months. Aside from that, the actual implementation of the various knobs is known to be broken. There have been sporadic attempts at fixing things but these always stop short of reaching a mergable state. Therefore this wholesale removal with the hopes of spurring people who care to come forward once again and work on a coherent replacement. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/1326104915.2442.53.camel@twins Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * Merge branch 'sched/urgent' into sched/coreIngo Molnar2012-05-171-0/+2
| |\ | | | | | | | | | | | | | | | | | | Merge reason: bring together all the pending scheduler bits, for the sched/numa changes. Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/debug: Fix printing large integers on 32-bit platformsPeter Zijlstra2012-05-141-2/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Some numbers like nr_running and nr_uninterruptible are fundamentally unsigned since its impossible to have a negative amount of tasks, yet we still print them as signed to easily recognise the underflow condition. rq->nr_uninterruptible has 'special' accounting and can in fact very easily become negative on a per-cpu basis. It was noted that since the P() macro assumes things are long long and the promotion of unsigned 'int/long' to long long on 32bit doesn't sign extend we print silly large numbers instead of the easier to read signed numbers. Therefore extend the P() macro to not require the sign extention. Reported-by: Diwakar Tundlam <dtundlam@nvidia.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-gk5tm8t2n4ix2vkpns42uqqp@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/fair: Improve the ->group_imb logicPeter Zijlstra2012-05-141-6/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Group imbalance is meant to deal with situations where affinity masks and sched domains don't align well, such as 3 cpus from one group and 6 from another. In this case the domain based balancer will want to put an equal amount of tasks on each side even though they don't have equal cpus. Currently group_imb is set whenever two cpus of a group have a weight difference of at least one avg task and the heaviest cpu has at least two tasks. A group with imbalance set will always be picked as busiest and a balance pass will be forced. The problem is that even if there are no affinity masks this stuff can trigger and cause weird balancing decisions, eg. the observed behaviour was that of 6 cpus, 5 had 2 and 1 had 3 tasks, due to the difference of 1 avg load (they all had the same weight) and nr_running being >1 the group_imbalance logic triggered and did the weird thing of pulling more load instead of trying to move the 1 excess task to the other domain of 6 cpus that had 5 cpu with 2 tasks and 1 cpu with 1 task. Curb the group_imbalance stuff by making the nr_running condition weaker by also tracking the min_nr_running and using the difference in nr_running over the set instead of the absolute max nr_running. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-9s7dedozxo8kjsb9kqlrukkf@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/nohz: Fix rq->cpu_load[] calculationsPeter Zijlstra2012-05-143-16/+41
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | While investigating why the load-balancer did funny I found that the rq->cpu_load[] tables were completely screwy.. a bit more digging revealed that the updates that got through were missing ticks followed by a catchup of 2 ticks. The catchup assumes the cpu was idle during that time (since only nohz can cause missed ticks and the machine is idle etc..) this means that esp. the higher indices were significantly lower than they ought to be. The reason for this is that its not correct to compare against jiffies on every jiffy on any other cpu than the cpu that updates jiffies. This patch cludges around it by only doing the catch-up stuff from nohz_idle_balance() and doing the regular stuff unconditionally from the tick. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: pjt@google.com Cc: Venkatesh Pallipadi <venki@google.com> Link: http://lkml.kernel.org/n/tip-tp4kj18xdd5aj4vvj0qg55s2@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/numa: Don't scale the imbalancePeter Zijlstra2012-05-141-6/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | It's far too easy to get ridiculously large imbalance pct when you scale it like that. Use a fixed 125% for now. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-zsriaft1dv7hhboyrpvqjy6s@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/fair: Revert sched-domain iteration breakagePeter Zijlstra2012-05-142-14/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patches c22402a2f ("sched/fair: Let minimally loaded cpu balance the group") and 0ce90475 ("sched/fair: Add some serialization to the sched_domain load-balance walk") are horribly broken so revert them. The problem is that while it sounds good to have the minimally loaded cpu do the pulling of more load, the way we walk the domains there is absolutely no guarantee this cpu will actually get to the domain. In fact its very likely it wont. Therefore the higher up the tree we get, the less likely it is we'll balance at all. The first of mask always walks up, while sucky in that it accumulates load on the first cpu and needs extra passes to spread it out at least guarantees a cpu gets up that far and load-balancing happens at all. Since its now always the first and idle cpus should always be able to balance so they get a task as fast as possible we can also do away with the added serialization. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-rpuhs5s56aiv1aw7khv9zkw6@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/numa: Fix the new NUMA topology bitsPeter Zijlstra2012-05-141-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There's no need to convert a node number to a node number by pretending its a cpu number.. Reported-by: Yinghai Lu <yinghai@kernel.org> Reported-and-Tested-by: Greg Pearson <greg.pearson@hp.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-0sqhrht34phowgclj12dgk8h@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/numa: Rewrite the CONFIG_NUMA sched domain supportPeter Zijlstra2012-05-091-95/+185
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The current code groups up to 16 nodes in a level and then puts an ALLNODES domain spanning the entire tree on top of that. This doesn't reflect the numa topology and esp for the smaller not-fully-connected machines out there today this might make a difference. Therefore, build a proper numa topology based on node_distance(). Since there's no fixed numa layers anymore, the static SD_NODE_INIT and SD_ALLNODES_INIT aren't usable anymore, the new code tries to construct something similar and scales some values either on the number of cpus in the domain and/or the node_distance() ratio. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Anton Blanchard <anton@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: David Howells <dhowells@redhat.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: linux-alpha@vger.kernel.org Cc: linux-ia64@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-mips@linux-mips.org Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-sh@vger.kernel.org Cc: Matt Turner <mattst88@gmail.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Richard Henderson <rth@twiddle.net> Cc: sparclinux@vger.kernel.org Cc: Tony Luck <tony.luck@intel.com> Cc: x86@kernel.org Cc: Dimitri Sivanich <sivanich@sgi.com> Cc: Greg Pearson <greg.pearson@hp.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: bob.picco@oracle.com Cc: chris.mason@oracle.com Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/n/tip-r74n3n8hhuc2ynbrnp3vt954@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/fair: Propagate 'struct lb_env' usage into find_busiest_groupPeter Zijlstra2012-05-091-93/+82
| | | | | | | | | | | | | | | | | | | | | | | | More function argument passing reduction. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-v66ivjfqdiqdso01lqgqx6qf@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/fair: Add some serialization to the sched_domain load-balance walkPeter Zijlstra2012-05-092-2/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since the sched_domain walk is completely unserialized (!SD_SERIALIZE) it is possible that multiple cpus in the group get elected to do the next level. Avoid this by adding some serialization. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-vqh9ai6s0ewmeakjz80w4qz6@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched/fair: Let minimally loaded cpu balance the groupPeter Zijlstra2012-05-091-5/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently we let the leftmost (or first idle) cpu ascend the sched_domain tree and perform load-balancing. The result is that the busiest cpu in the group might be performing this function and pull more load to itself. The next load balance pass will then try to equalize this again. Change this to pick the least loaded cpu to perform higher domain balancing. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-v8zlrmgmkne3bkcy9dej1fvm@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Change rq->nr_running to unsigned intPeter Zijlstra2012-05-093-8/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since there's a PID space limit of 30bits (see futex.h:FUTEX_TID_MASK) and allocating that many tasks (assuming a lower bound of 2 pages per task) would still take 8T of memory it seems reasonable to say that unsigned int is sufficient for rq->nr_running. When we do get anywhere near that amount of tasks I suspect other things would go funny, load-balancer load computations would really need to be hoisted to 128bit etc. So save a few bytes and convert rq->nr_running and friends to unsigned int. Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-y3tvyszjdmbibade5bw8zl81@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | sched: Update documentation and commentsHiroshi Shimamoto2012-05-071-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | Change sched_*.c to sched/*.c in documentation and comments. Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/4F795CAC.9080206@ct.jp.nec.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | Merge branch 'linus' into sched/coreIngo Molnar2012-05-0711-53/+87
| |\ \ | | | | | | | | | | | | | | | | | | | | Merge reason: We were on a pretty old base, refresh before moving on. Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * \ \ Merge branch 'tip/sched/core' of ↵Ingo Molnar2012-04-141-30/+26
| |\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace into sched/core Pull a scheduler optimization commit from Steven Rostedt. Signed-off-by: Ingo Molnar <mingo@kernel.org>
| | * | | sched_rt: Avoid unnecessary dequeue and enqueue of pushable tasks in ↵Kirill Tkhai2012-04-121-30/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | set_cpus_allowed_rt() Migration status depends on a difference of weight from 0 and 1. If weight > 1 (<= 1) and old weight <= 1 (> 1) then task becomes pushable (or not pushable). We are not insterested in its exact values, is it 3 or 4, for example. Now if we are changing affinity from a set of 3 cpus to a set of 4, the- task will be dequeued and enqueued sequentially without important difference in comparison with initial state. The only difference is in internal representation of plist queue of pushable tasks and the fact that the task may won't be the first in a sequence of the same priority tasks. But it seems to me it gives nothing. Link: http://lkml.kernel.org/r/273741334120764@web83.yandex.ru Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Tkhai Kirill <tkhai@yandex.ru> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* | | | | Merge branch 'perf-core-for-linus' of ↵Linus Torvalds2012-05-228-499/+874
|\ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf changes from Ingo Molnar: "Lots of changes: - (much) improved assembly annotation support in perf report, with jump visualization, searching, navigation, visual output improvements and more. - kernel support for AMD IBS PMU hardware features. Notably 'perf record -e cycles:p' and 'perf top -e cycles:p' should work without skid now, like PEBS does on the Intel side, because it takes advantage of IBS transparently. - the libtracevents library: it is the first step towards unifying tracing tooling and perf, and it also gives a tracing library for external tools like powertop to rely on. - infrastructure: various improvements and refactoring of the UI modules and related code - infrastructure: cleanup and simplification of the profiling targets code (--uid, --pid, --tid, --cpu, --all-cpus, etc.) - tons of robustness fixes all around - various ftrace updates: speedups, cleanups, robustness improvements. - typing 'make' in tools/ will now give you a menu of projects to build and a short help text to explain what each does. - ... and lots of other changes I forgot to list. The perf record make bzImage + perf report regression you reported should be fixed." * 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (166 commits) tracing: Remove kernel_lock annotations tracing: Fix initial buffer_size_kb state ring-buffer: Merge separate resize loops perf evsel: Create events initially disabled -- again perf tools: Split term type into value type and term type perf hists: Fix callchain ip printf format perf target: Add uses_mmap field ftrace: Remove selecting FRAME_POINTER with FUNCTION_TRACER ftrace/x86: Have x86 ftrace use the ftrace_modify_all_code() ftrace: Make ftrace_modify_all_code() global for archs to use ftrace: Return record ip addr for ftrace_location() ftrace: Consolidate ftrace_location() and ftrace_text_reserved() ftrace: Speed up search by skipping pages by address ftrace: Remove extra helper functions ftrace: Sort all function addresses, not just per page tracing: change CPU ring buffer state from tracing_cpumask tracing: Check return value of tracing_dentry_percpu() ring-buffer: Reset head page before running self test ring-buffer: Add integrity check at end of iter read ring-buffer: Make addition of pages in ring buffer atomic ...
| * \ \ \ \ Merge branch 'tip/perf/core-2' of ↵Ingo Molnar2012-05-212-29/+17
| |\ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace into perf/core
| | * | | | | tracing: Remove kernel_lock annotationsRichard Weinberger2012-05-191-2/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The BKL is gone, these annotations are useless. Link: http://lkml.kernel.org/r/1320654202-4433-1-git-send-email-richard@nod.at Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| | * | | | | tracing: Fix initial buffer_size_kb stateVaibhav Nagarnaik2012-05-191-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Make sure that the state of buffer_size_kb is initialized correctly and returns actual size of the ring buffer. Link: http://lkml.kernel.org/r/1336066834-1673-1-git-send-email-vnagarnaik@google.com Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Laurent Chavey <chavey@google.com> Cc: Justin Teravest <teravest@google.com> Cc: David Sharp <dhsharp@google.com> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| | * | | | | ring-buffer: Merge separate resize loopsVaibhav Nagarnaik2012-05-191-26/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are 2 separate loops to resize cpu buffers that are online and offline. Merge them to make the code look better. Also change the name from update_completion to update_done to allow shorter lines. Link: http://lkml.kernel.org/r/1337372991-14783-1-git-send-email-vnagarnaik@google.com Cc: Laurent Chavey <chavey@google.com> Cc: Justin Teravest <teravest@google.com> Cc: David Sharp <dhsharp@google.com> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | Merge branch 'perf/core' of ↵Ingo Molnar2012-05-2113-54/+92
| |\ \ \ \ \ \ | | |/ / / / / | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core Fixes for perf/core: - Rename some perf_target methods to avoid double negation, from Namhyung Kim. - Revert change to use per task events with inheritance, from Namhyung Kim. - Events should start disabled till children starts running, from David Ahern. Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org>
| | * | | | | Merge remote-tracking branch 'tip/perf/urgent' into perf/coreArnaldo Carvalho de Melo2012-05-1813-54/+92
| | |\ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Merge reason: We are going to queue up a dependent patch: "perf tools: Move parse event automated tests to separated object" That depends on: commit e7c72d8 perf tools: Add 'G' and 'H' modifiers to event parsing Conflicts: tools/perf/builtin-stat.c Conflicted with the recent 'perf_target' patches when checking the result of perf_evsel open routines to see if a retry is needed to cope with older kernels where the exclude guest/host perf_event_attr bits were not used. Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
| * | | | | | | ftrace: Remove selecting FRAME_POINTER with FUNCTION_TRACERSteven Rostedt2012-05-161-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The function tracer will enable the -pg option with gcc, which requires that frame pointers. When FRAME_POINTER is defined in the kernel config it adds the gcc option -fno-omit-frame-pointer which causes some problems on some architectures. For those architectures, the FRAME_POINTER select was not set. When FUNCTION_TRACER was selected on these architectures that can not have -fno-omit-frame-pointer, the -pg option is still set. But when FRAME_POINTER is not selected, the kernel config would add the gcc option -fomit-frame-pointer. Adding this option is incompatible with -pg even on archs that do not need frame pointers with -pg. The answer to this was to just not add either -fno-omit-frame-pointer or -fomit-frame-pointer on these archs that want function tracing but do not set FRAME_POINTER. As it turns out, for archs that require frame pointers for function tracing, the same can be used. If gcc requires frame pointers with -pg, it will simply add it. The best thing to do is not select FRAME_POINTER when function tracing is selected, and let gcc add it if needed. Only add the -fno-omit-frame-pointer when something else selects FRAME_POINTER, but do not add -fomit-frame-pointer if function tracing is selected. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | ftrace/x86: Have x86 ftrace use the ftrace_modify_all_code()Steven Rostedt2012-05-161-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | To remove duplicate code, have the ftrace arch_ftrace_update_code() use the generic ftrace_modify_all_code(). This requires that the default ftrace_replace_code() becomes a weak function so that an arch may override it. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | ftrace: Make ftrace_modify_all_code() global for archs to useSteven Rostedt2012-05-161-8/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Rename __ftrace_modify_code() to ftrace_modify_all_code() and make it global for all archs to use. This will remove the duplication of code, as archs that can modify code without stop_machine() can use it directly outside of the stop_machine() call. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | ftrace: Return record ip addr for ftrace_location()Steven Rostedt2012-05-161-6/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ftrace_location() is passed an addr, and returns 1 if the addr is on a ftrace nop (or caller to ftrace_caller), and 0 otherwise. To let kprobes know if it should move a breakpoint or not, it must return the actual addr that is the start of the ftrace nop. This way a kprobe placed on the location of a ftrace nop, can instead be placed on the instruction after the nop. Even if the probe addr is on the second or later byte of the nop, it can simply be moved forward. Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | ftrace: Consolidate ftrace_location() and ftrace_text_reserved()Steven Rostedt2012-05-161-40/+40
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Both ftrace_location() and ftrace_text_reserved() do basically the same thing. They search to see if an address is in the ftace table (contains an address that may change from nop to call ftrace_caller). The difference is that ftrace_location() searches a single address, but ftrace_text_reserved() searches a range. This also makes the ftrace_text_reserved() faster as it now uses a bsearch() instead of linearly searching all the addresses within a page. Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | ftrace: Speed up search by skipping pages by addressSteven Rostedt2012-05-161-6/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As all records in a page of the ftrace table are sorted, we can speed up the search algorithm by checking if the address to look for falls in between the first and last record ip on the page. This speeds up both the ftrace_location() and ftrace_text_reserved() algorithms, as it can skip full pages when the search address is not in them. Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | ftrace: Remove extra helper functionsSteven Rostedt2012-05-161-37/+24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The ftrace_record_ip() and ftrace_alloc_dyn_node() were from the time of the ftrace daemon. Although they were still used, they still make things a bit more complex than necessary. Move the code into the one function that uses it, and remove the helper functions. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | ftrace: Sort all function addresses, not just per pageSteven Rostedt2012-05-161-12/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Instead of just sorting the ip's of the functions per ftrace page, sort the entire list before adding them to the ftrace pages. This will allow the bsearch algorithm to be sped up as it can also sort by pages, not just records within a page. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | tracing: change CPU ring buffer state from tracing_cpumaskVaibhav Nagarnaik2012-05-161-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | According to Documentation/trace/ftrace.txt: tracing_cpumask: This is a mask that lets the user only trace on specified CPUS. The format is a hex string representing the CPUS. The tracing_cpumask currently doesn't affect the tracing state of per-CPU ring buffers. This patch enables/disables CPU recording as its corresponding bit in tracing_cpumask is set/unset. Link: http://lkml.kernel.org/r/1336096792-25373-3-git-send-email-vnagarnaik@google.com Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Laurent Chavey <chavey@google.com> Cc: Justin Teravest <teravest@google.com> Cc: David Sharp <dhsharp@google.com> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | tracing: Check return value of tracing_dentry_percpu()Namhyung Kim2012-05-161-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If tracing_dentry_percpu() failed, tracing_init_debugfs_percpu() will try to create each cpu directories on debugfs' root directory as d_percpu is NULL. Link: http://lkml.kernel.org/r/1335143517-2285-1-git-send-email-namhyung.kim@lge.com Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Namhyung Kim <namhyung.kim@lge.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | ring-buffer: Reset head page before running self testSteven Rostedt2012-05-161-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When the ring buffer does its consistency test on itself, it removes the head page, runs the tests, and then adds it back to what the "head_page" pointer was. But because the head_page pointer may lack behind the real head page (held by the link list pointer). The reset may be incorrect. Instead, if the head_page exists (it does not on first allocation) reset it back to the real head page before running the consistency tests. Then it will be put back to its original location after the tests are complete. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | ring-buffer: Add integrity check at end of iter readSteven Rostedt2012-05-161-0/+29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There use to be ring buffer integrity checks after updating the size of the ring buffer. But now that the ring buffer can modify the size while the system is running, the integrity checks were removed, as they require the ring buffer to be disabed to perform the check. Move the integrity check to the reading of the ring buffer via the iterator reads (the "trace" file). As reading via an iterator requires disabling the ring buffer, it is a perfect place to have it. If the ring buffer happens to be disabled when updating the size, we still perform the integrity check. Cc: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | ring-buffer: Make addition of pages in ring buffer atomicVaibhav Nagarnaik2012-05-161-25/+77
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds the capability to add new pages to a ring buffer atomically while write operations are going on. This makes it possible to expand the ring buffer size without reinitializing the ring buffer. The new pages are attached between the head page and its previous page. Link: http://lkml.kernel.org/r/1336096792-25373-2-git-send-email-vnagarnaik@google.com Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Laurent Chavey <chavey@google.com> Cc: Justin Teravest <teravest@google.com> Cc: David Sharp <dhsharp@google.com> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | ring-buffer: Make removal of ring buffer pages atomicVaibhav Nagarnaik2012-05-162-76/+209
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds the capability to remove pages from a ring buffer without destroying any existing data in it. This is done by removing the pages after the tail page. This makes sure that first all the empty pages in the ring buffer are removed. If the head page is one in the list of pages to be removed, then the page after the removed ones is made the head page. This removes the oldest data from the ring buffer and keeps the latest data around to be read. To do this in a non-racey manner, tracing is stopped for a very short time while the pages to be removed are identified and unlinked from the ring buffer. The pages are freed after the tracing is restarted to minimize the time needed to stop tracing. The context in which the pages from the per-cpu ring buffer are removed runs on the respective CPU. This minimizes the events not traced to only NMI trace contexts. Link: http://lkml.kernel.org/r/1336096792-25373-1-git-send-email-vnagarnaik@google.com Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Laurent Chavey <chavey@google.com> Cc: Justin Teravest <teravest@google.com> Cc: David Sharp <dhsharp@google.com> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | tracing: Clean up tracing_mark_write()Steven Rostedt2012-05-161-13/+11
| |/ / / / / / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On gcc 4.5 the function tracing_mark_write() would give a warning of page2 being uninitialized. This is due to a bug in gcc because the logic prevents page2 from being used uninitialized, and gcc 4.6+ does not complain (correctly). Instead of adding a "unitialized" around page2, which could show a bug later on, I combined page1 and page2 into an array map_pages[]. This binds the two and the two are modified according to nr_pages (what gcc 4.5 seems to ignore). This no longer gives a warning with gcc 4.5 nor with gcc 4.6. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | Merge branch 'tip/perf/core' of ↵Ingo Molnar2012-05-092-100/+18
| |\ \ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace into perf/core
| | * | | | | | tracing: Remove ftrace_disable/enable_cpu()Steven Rostedt2012-05-081-42/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The ftrace_disable_cpu() and ftrace_enable_cpu() functions were needed back before the ring buffer was lockless. Now that the ring buffer is lockless (and has been for some time), these functions serve no purpose, and unnecessarily slow down operations of the tracer. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| | * | | | | | tracing: Use seq_*_private interface for some seq filesJiri Olsa2012-05-082-58/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It's appropriate to use __seq_open_private interface to open some of trace seq files, because it covers all steps we are duplicating in tracing code - zallocating the iterator and setting it as seq_file's private. Using this for following files: trace available_filter_functions enabled_functions Link: http://lkml.kernel.org/r/1335342219-2782-5-git-send-email-jolsa@redhat.com Signed-off-by: Jiri Olsa <jolsa@redhat.com> [ Fixed warnings for: kernel/trace/trace.c: In function '__tracing_open': kernel/trace/trace.c:2418:11: warning: unused variable 'ret' [-Wunused-variable] kernel/trace/trace.c:2417:19: warning: unused variable 'm' [-Wunused-variable] ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| * | | | | | | sched, perf: Use a single callback into the schedulerPeter Zijlstra2012-05-092-12/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We can easily use a single callback for both sched-in and sched-out. This reduces the code footprint in the scheduler path as well as removes the PMU black spot otherwise present between the out and in callback. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-o56ajxp1edwqg6x9d31wb805@git.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | | | | | perf: Pass last sampling period to perf_sample_data_init()Robert Richter2012-05-091-5/+4
| |/ / / / / / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We always need to pass the last sample period to perf_sample_data_init(), otherwise the event distribution will be wrong. Thus, modifiyng the function interface with the required period as argument. So basically a pattern like this: perf_sample_data_init(&data, ~0ULL); data.period = event->hw.last_period; will now be like that: perf_sample_data_init(&data, ~0ULL, event->hw.last_period); Avoids unininitialized data.period and simplifies code. Signed-off-by: Robert Richter <robert.richter@amd.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1333390758-10893-3-git-send-email-robert.richter@amd.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | | | | Merge branch 'tip/perf/core-4' of ↵Ingo Molnar2012-05-074-200/+435
| |\ \ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace into perf/core
| | * | | | | | ring-buffer: Add per_cpu ring buffer control filesVaibhav Nagarnaik2012-04-233-147/+293
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add a debugfs entry under per_cpu/ folder for each cpu called buffer_size_kb to control the ring buffer size for each CPU independently. If the global file buffer_size_kb is used to set size, the individual ring buffers will be adjusted to the given size. The buffer_size_kb will report the common size to maintain backward compatibility. If the buffer_size_kb file under the per_cpu/ directory is used to change buffer size for a specific CPU, only the size of the respective ring buffer is updated. When tracing/buffer_size_kb is read, it reports 'X' to indicate that sizes of per_cpu ring buffers are not equivalent. Link: http://lkml.kernel.org/r/1328212844-11889-1-git-send-email-vnagarnaik@google.com Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Michael Rubin <mrubin@google.com> Cc: David Sharp <dhsharp@google.com> Cc: Justin Teravest <teravest@google.com> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| | * | | | | | tracing: Remove an unneeded check in trace_seq_buffer()Dan Carpenter2012-04-231-4/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | memcpy() returns a pointer to "bug". Hopefully, it's not NULL here or we would already have Oopsed. Link: http://lkml.kernel.org/r/20120420063145.GA22649@elgon.mountain Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| | * | | | | | tracing: Add percpu buffers for trace_printk()Steven Rostedt2012-04-233-49/+141
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, trace_printk() uses a single buffer to write into to calculate the size and format needed to save the trace. To do this safely in an SMP environment, a spin_lock() is taken to only allow one writer at a time to the buffer. But this could also affect what is being traced, and add synchronization that would not be there otherwise. Ideally, using percpu buffers would be useful, but since trace_printk() is only used in development, having per cpu buffers for something never used is a waste of space. Thus, the use of the trace_bprintk() format section is changed to be used for static fmts as well as dynamic ones. Then at boot up, we can check if the section that holds the trace_printk formats is non-empty, and if it does contain something, then we know a trace_printk() has been added to the kernel. At this time the trace_printk per cpu buffers are allocated. A check is also done at module load time in case a module is added that contains a trace_printk(). Once the buffers are allocated, they are never freed. If you use a trace_printk() then you should know what you are doing. A buffer is made for each type of context: normal softirq irq nmi The context is checked and the appropriate buffer is used. This allows for totally lockless usage of trace_printk(), and they no longer even disable interrupts. Requested-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>