diff options
Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 162 |
1 files changed, 85 insertions, 77 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 9e5bab29685f..ae3afa2cc421 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -692,7 +692,7 @@ kernel/dma/contiguous.c cma_pernuma=nn[MG] - [ARM64,KNL,CMA] + [KNL,CMA] Sets the size of kernel per-numa memory area for contiguous memory allocations. A value of 0 disables per-numa CMA altogether. And If this option is not @@ -818,20 +818,6 @@ Format: <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] - cpu0_hotplug [X86] Turn on CPU0 hotplug feature when - CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off. - Some features depend on CPU0. Known dependencies are: - 1. Resume from suspend/hibernate depends on CPU0. - Suspend/hibernate will fail if CPU0 is offline and you - need to online CPU0 before suspend/hibernate. - 2. PIC interrupts also depend on CPU0. CPU0 can't be - removed if a PIC interrupt is detected. - It's said poweroff/reboot may depend on CPU0 on some - machines although I haven't seen such issues so far - after CPU0 is offline on a few tested machines. - If the dependencies are under your control, you can - turn on cpu0_hotplug. - cpuidle.off=1 [CPU_IDLE] disable the cpuidle sub-system @@ -852,6 +838,12 @@ on every CPU online, such as boot, and resume from suspend. Default: 10000 + cpuhp.parallel= + [SMP] Enable/disable parallel bringup of secondary CPUs + Format: <bool> + Default is enabled if CONFIG_HOTPLUG_PARALLEL=y. Otherwise + the parameter has no effect. + crash_kexec_post_notifiers Run kdump after running panic-notifiers and dumping kmsg. This only for the users who doubt kdump always @@ -4736,43 +4728,6 @@ the propagation of recent CPU-hotplug changes up the rcu_node combining tree. - rcutree.use_softirq= [KNL] - If set to zero, move all RCU_SOFTIRQ processing to - per-CPU rcuc kthreads. Defaults to a non-zero - value, meaning that RCU_SOFTIRQ is used by default. - Specify rcutree.use_softirq=0 to use rcuc kthreads. - - But note that CONFIG_PREEMPT_RT=y kernels disable - this kernel boot parameter, forcibly setting it - to zero. - - rcutree.rcu_fanout_exact= [KNL] - Disable autobalancing of the rcu_node combining - tree. This is used by rcutorture, and might - possibly be useful for architectures having high - cache-to-cache transfer latencies. - - rcutree.rcu_fanout_leaf= [KNL] - Change the number of CPUs assigned to each - leaf rcu_node structure. Useful for very - large systems, which will choose the value 64, - and for NUMA systems with large remote-access - latencies, which will choose a value aligned - with the appropriate hardware boundaries. - - rcutree.rcu_min_cached_objs= [KNL] - Minimum number of objects which are cached and - maintained per one CPU. Object size is equal - to PAGE_SIZE. The cache allows to reduce the - pressure to page allocator, also it makes the - whole algorithm to behave better in low memory - condition. - - rcutree.rcu_delay_page_cache_fill_msec= [KNL] - Set the page-cache refill delay (in milliseconds) - in response to low-memory conditions. The range - of permitted values is in the range 0:100000. - rcutree.jiffies_till_first_fqs= [KNL] Set delay from grace-period initialization to first attempt to force quiescent states. @@ -4811,21 +4766,6 @@ When RCU_NOCB_CPU is set, also adjust the priority of NOCB callback kthreads. - rcutree.rcu_divisor= [KNL] - Set the shift-right count to use to compute - the callback-invocation batch limit bl from - the number of callbacks queued on this CPU. - The result will be bounded below by the value of - the rcutree.blimit kernel parameter. Every bl - callbacks, the softirq handler will exit in - order to allow the CPU to do other work. - - Please note that this callback-invocation batch - limit applies only to non-offloaded callback - invocation. Offloaded callbacks are instead - invoked in the context of an rcuoc kthread, which - scheduler will preempt as it does any other task. - rcutree.nocb_nobypass_lim_per_jiffy= [KNL] On callback-offloaded (rcu_nocbs) CPUs, RCU reduces the lock contention that would @@ -4839,14 +4779,6 @@ the ->nocb_bypass queue. The definition of "too many" is supplied by this kernel boot parameter. - rcutree.rcu_nocb_gp_stride= [KNL] - Set the number of NOCB callback kthreads in - each group, which defaults to the square root - of the number of CPUs. Larger numbers reduce - the wakeup overhead on the global grace-period - kthread, but increases that same overhead on - each group's NOCB grace-period kthread. - rcutree.qhimark= [KNL] Set threshold of queued RCU callbacks beyond which batch limiting is disabled. @@ -4864,6 +4796,56 @@ on rcutree.qhimark at boot time and to zero to disable more aggressive help enlistment. + rcutree.rcu_delay_page_cache_fill_msec= [KNL] + Set the page-cache refill delay (in milliseconds) + in response to low-memory conditions. The range + of permitted values is in the range 0:100000. + + rcutree.rcu_divisor= [KNL] + Set the shift-right count to use to compute + the callback-invocation batch limit bl from + the number of callbacks queued on this CPU. + The result will be bounded below by the value of + the rcutree.blimit kernel parameter. Every bl + callbacks, the softirq handler will exit in + order to allow the CPU to do other work. + + Please note that this callback-invocation batch + limit applies only to non-offloaded callback + invocation. Offloaded callbacks are instead + invoked in the context of an rcuoc kthread, which + scheduler will preempt as it does any other task. + + rcutree.rcu_fanout_exact= [KNL] + Disable autobalancing of the rcu_node combining + tree. This is used by rcutorture, and might + possibly be useful for architectures having high + cache-to-cache transfer latencies. + + rcutree.rcu_fanout_leaf= [KNL] + Change the number of CPUs assigned to each + leaf rcu_node structure. Useful for very + large systems, which will choose the value 64, + and for NUMA systems with large remote-access + latencies, which will choose a value aligned + with the appropriate hardware boundaries. + + rcutree.rcu_min_cached_objs= [KNL] + Minimum number of objects which are cached and + maintained per one CPU. Object size is equal + to PAGE_SIZE. The cache allows to reduce the + pressure to page allocator, also it makes the + whole algorithm to behave better in low memory + condition. + + rcutree.rcu_nocb_gp_stride= [KNL] + Set the number of NOCB callback kthreads in + each group, which defaults to the square root + of the number of CPUs. Larger numbers reduce + the wakeup overhead on the global grace-period + kthread, but increases that same overhead on + each group's NOCB grace-period kthread. + rcutree.rcu_kick_kthreads= [KNL] Cause the grace-period kthread to get an extra wake_up() if it sleeps three times longer than @@ -4871,6 +4853,13 @@ This wake_up() will be accompanied by a WARN_ONCE() splat and an ftrace_dump(). + rcutree.rcu_resched_ns= [KNL] + Limit the time spend invoking a batch of RCU + callbacks to the specified number of nanoseconds. + By default, this limit is checked only once + every 32 callbacks in order to limit the pain + inflicted by local_clock() overhead. + rcutree.rcu_unlock_delay= [KNL] In CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels, this specifies an rcu_read_unlock()-time delay @@ -4885,6 +4874,16 @@ rcu_node tree with an eye towards determining why a new grace period has not yet started. + rcutree.use_softirq= [KNL] + If set to zero, move all RCU_SOFTIRQ processing to + per-CPU rcuc kthreads. Defaults to a non-zero + value, meaning that RCU_SOFTIRQ is used by default. + Specify rcutree.use_softirq=0 to use rcuc kthreads. + + But note that CONFIG_PREEMPT_RT=y kernels disable + this kernel boot parameter, forcibly setting it + to zero. + rcuscale.gp_async= [KNL] Measure performance of asynchronous grace-period primitives such as call_rcu(). @@ -5087,8 +5086,17 @@ rcutorture.stall_cpu_block= [KNL] Sleep while stalling if set. This will result - in warnings from preemptible RCU in addition - to any other stall-related activity. + in warnings from preemptible RCU in addition to + any other stall-related activity. Note that + in kernels built with CONFIG_PREEMPTION=n and + CONFIG_PREEMPT_COUNT=y, this parameter will + cause the CPU to pass through a quiescent state. + Given CONFIG_PREEMPTION=n, this will suppress + RCU CPU stall warnings, but will instead result + in scheduling-while-atomic splats. + + Use of this module parameter results in splats. + rcutorture.stall_cpu_holdoff= [KNL] Time to wait (s) after boot before inducing stall. |