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* [armv7] PIC by default + [aarch64-linux] T11276 metric increaseMoritz Angermann2021-03-291-1/+1
| | | | | Metric Increase: T11276
* Allocate Adjustors and mark them readable in two stepsMoritz Angermann2021-03-292-1/+13
| | | | | | | | | This drops allocateExec for darwin, and replaces it with a alloc, write, mark executable strategy instead. This prevents us from trying to allocate an executable range and then write to it, which X^W will prohibit on darwin. This will *only* work if we can use mmap.
* Generate GHCi bytecode from STG instead of Core and support unboxedLuite Stegeman2021-03-202-0/+75
| | | | | | tuples and sums. fixes #1257
* rts: Gradually return retained memory to the OSMatthew Pickering2021-03-101-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Related to #19381 #19359 #14702 After a spike in memory usage we have been conservative about returning allocated blocks to the OS in case we are still allocating a lot and would end up just reallocating them. The result of this was that up to 4 * live_bytes of blocks would be retained once they were allocated even if memory usage ended up a lot lower. For a heap of size ~1.5G, this would result in OS memory reporting 6G which is both misleading and worrying for users. In long-lived server applications this results in consistent high memory usage when the live data size is much more reasonable (for example ghcide) Therefore we have a new (2021) strategy which starts by retaining up to 4 * live_bytes of blocks before gradually returning uneeded memory back to the OS on subsequent major GCs which are NOT caused by a heap overflow. Each major GC which is NOT caused by heap overflow increases the consec_idle_gcs counter and the amount of memory which is retained is inversely proportional to this number. By default the excess memory retained is oldGenFactor (controlled by -F) / 2 ^ (consec_idle_gcs * returnDecayFactor) On a major GC caused by a heap overflow, the `consec_idle_gcs` variable is reset to 0 (as we could continue to allocate more, so retaining all the memory might make sense). Therefore setting bigger values for `-Fd` makes the rate at which memory is returned slower. Smaller values make it get returned faster. Setting `-Fd0` disables the memory return completely, which is the behaviour of older GHC versions. The default is `-Fd4` which results in the following scaling: > mapM print [(x, 1/ (2**(x / 4))) | x <- [1 :: Double ..20]] (1.0,0.8408964152537146) (2.0,0.7071067811865475) (3.0,0.5946035575013605) (4.0,0.5) (5.0,0.4204482076268573) (6.0,0.35355339059327373) (7.0,0.29730177875068026) (8.0,0.25) (9.0,0.21022410381342865) (10.0,0.17677669529663687) (11.0,0.14865088937534013) (12.0,0.125) (13.0,0.10511205190671433) (14.0,8.838834764831843e-2) (15.0,7.432544468767006e-2) (16.0,6.25e-2) (17.0,5.255602595335716e-2) (18.0,4.4194173824159216e-2) (19.0,3.716272234383503e-2) (20.0,3.125e-2) So after 13 consecutive GCs only 0.1 of the maximum memory used will be retained. Further to this decay factor, the amount of memory we attempt to retain is also influenced by the GC strategy for the oldest generation. If we are using a copying strategy then we will need at least 2 * live_bytes for copying to take place, so we always keep that much. If using compacting or nonmoving then we need a lower number, so we just retain at least `1.2 * live_bytes` for some protection. In future we might want to make this behaviour more aggressive, some relevant literature is > Ulan Degenbaev, Jochen Eisinger, Manfred Ernst, Ross McIlroy, and Hannes Payer. 2016. Idle time garbage collection scheduling. SIGPLAN Not. 51, 6 (June 2016), 570–583. DOI:https://doi.org/10.1145/2980983.2908106 which describes the "memory reducer" in the V8 javascript engine which on an idle collection immediately returns as much memory as possible.
* eventlog: Add BLOCKS_SIZE eventMatthew Pickering2021-03-081-0/+1
| | | | | | | | | | | | | The BLOCKS_SIZE event reports the size of the currently allocated blocks in bytes. It is like the HEAP_SIZE event, but reports about the blocks rather than megablocks. You can work out the current heap fragmentation by looking at the difference between HEAP_SIZE and BLOCKS_SIZE. Fixes #19357
* eventlog: Add MEM_RETURN event to give information about fragmentationMatthew Pickering2021-03-081-0/+2
| | | | | | | | | | | | | | See #19357 The event reports the * Current number of megablocks allocated * The number that the RTS thinks it needs * The number is managed to return to the OS When current > need then the difference is returned to the OS, the successful number of returned mblocks is reported by 'returned'. In a fragmented heap current > need but returned < current - need.
* Implement riscv64 LLVM backendAndreas Schwab2021-03-054-1/+141
| | | | This enables a registerised build for the riscv64 architecture.
* Add whereFrom and whereFrom# primopMatthew Pickering2021-03-031-0/+1
| | | | | | | | | | The `whereFrom` function provides a Haskell interface for using the information created by `-finfo-table-map`. Given a Haskell value, the info table address will be passed to the `lookupIPE` function in order to attempt to find the source location information for that particular closure. At the moment it's not possible to distinguish the absense of the map and a failed lookup.
* Add -finfo-table-map which maps info tables to source positionsMatthew Pickering2021-03-033-0/+37
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This new flag embeds a lookup table from the address of an info table to information about that info table. The main interface for consulting the map is the `lookupIPE` C function > InfoProvEnt * lookupIPE(StgInfoTable *info) The `InfoProvEnt` has the following structure: > typedef struct InfoProv_{ > char * table_name; > char * closure_desc; > char * ty_desc; > char * label; > char * module; > char * srcloc; > } InfoProv; > > typedef struct InfoProvEnt_ { > StgInfoTable * info; > InfoProv prov; > struct InfoProvEnt_ *link; > } InfoProvEnt; The source positions are approximated in a similar way to the source positions for DWARF debugging information. They are only approximate but in our experience provide a good enough hint about where the problem might be. It is therefore recommended to use this flag in conjunction with `-g<n>` for more accurate locations. The lookup table is also emitted into the eventlog when it is available as it is intended to be used with the `-hi` profiling mode. Using this flag will significantly increase the size of the resulting object file but only by a factor of 2-3x in our experience.
* Profiling by info table mode (-hi)Matthew Pickering2021-03-032-6/+8
| | | | | | | | This profiling mode creates bands by the address of the info table for each closure. This provides a much more fine-grained profiling output than any of the other profiling modes. The `-hi` profiling mode does not require a profiling build.
* Profiling: Allow heap profiling to be controlled dynamically.Matthew Pickering2021-03-033-0/+26
| | | | | | | | | | This patch exposes three new functions in `GHC.Profiling` which allow heap profiling to be enabled and disabled dynamically. 1. startHeapProfTimer - Starts heap profiling with the given RTS options 2. stopHeapProfTimer - Stops heap profiling 3. requestHeapCensus - Perform a heap census on the next context switch, regardless of whether the timer is enabled or not.
* Support auto-detection of MAX_REAL_FLOAT_REG and MAX_REAL_DOUBLE_REG up to 6ARATA Mizuki2021-03-021-2/+18
| | | | Fixes #17953
* Define TRY_ACQUIRE_LOCK correctly when non-threadedMatthew Pickering2021-03-021-3/+5
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* Remove the -xt heap profiling optionMatthew Pickering2021-02-271-1/+0
| | | | | | | It should be left to tooling to perform the filtering to remove these specific closure types from the profile if desired. Fixes #16795
* rts: Introduce --eventlog-flush-interval flagBen Gamari2021-02-271-0/+2
| | | | | | | This introduces a flag, --eventlog-flush-interval, which can be used to set an upper bound on the amount of time for which an eventlog event will remain enqueued. This can be useful in real-time monitoring settings.
* Move absentError into ghc-prim.Andreas Klebinger2021-02-261-0/+1
| | | | | | | | | | | | When using -fdicts-strict we generate references to absentError while compiling ghc-prim. However we always load ghc-prim before base so this caused linker errors. We simply solve this by moving absentError into ghc-prim. This does mean it's now a panic instead of an exception which can no longer be caught. But given that it should only be thrown if there is a compiler error that seems acceptable, and in fact we already do this for absentSumFieldError which has similar constraints.
* rts: Add generic block traversal function, listAllBlocksMatthew Pickering2021-02-181-0/+3
| | | | | | | | | This function is exposed in the RtsAPI.h so that external users have a blessed way to traverse all the different `bdescr`s which are known by the RTS. The main motivation is to use this function in ghc-debug but avoid having to expose the internal structure of a Capability in the API.
* rts: TraverseHeap: Simplify profiling headerDaniel Gröber2021-02-171-14/+5
| | | | | Having a union in the closure profiling header really just complicates things so get back to basics, we just have a single StgWord there for now.
* Fix typosBrian Wignall2021-02-061-1/+1
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* Move ioManager{Start,Wakeup,Die} to internal IOManager.hDuncan Coutts2021-01-251-12/+0
| | | | | | | | Move them from the external IOInterface.h to the internal IOManager.h. The functions are all in fact internal. They are not used from the base library at all. Remove ioManagerWakeup as an exported symbol. It is not used elsewhere.
* Rename includes/rts/IOManager.h to IOInterface.hDuncan Coutts2021-01-252-1/+1
| | | | | | | | | | | | | | | | | | | | | Naming is hard. Where we want to get to is to have a clear internal and external API for the IO manager within the RTS. What we have right now is just the external API (used in base for the Haskell side of the threaded IO manager impls) living in includes/rts/IOManager.h. We want to add a clear RTS internal API, which really ought to live in rts/IOManager.h. Several people think it's too confusing to have both: * includes/rts/IOManager.h for the external API * rts/IOManager.h for the internal API So the plan is to add rts/IOManager.{h,c} as the internal parts, and rename the external part to be includes/rts/IOInterface.h. It is admittidly not great to have .h files in includes/rts/ called "interface" since by definition, every .h fle under includes/ is an interface! Alternative naming scheme suggestions welcome!
* Force inlining of deRefStablePtr to silence warningsAndreas Klebinger2021-01-221-2/+2
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* rts: Initialize card table in newArray#Ben Gamari2021-01-171-13/+20
| | | | | | | | | | Previously we would leave the card table of new arrays uninitialized. This wasn't a soundness issue: at worst we would end up doing unnecessary scavenging during GC, after which the card table would be reset. That being said, it seems worth initializing this properly to avoid both unnecessary work and non-determinism. Fixes #19143.
* rts: gc: use mutex+condvar instead of spinlooks in gc entry/exitDouglas Wilson2021-01-171-14/+0
| | | | | | used timed wait on condition variable in waitForGcThreads fix dodgy timespec calculation
* rts: add timedWaitConditionDouglas Wilson2021-01-171-0/+1
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* rts: add max_n_todo_overflow internal counterDouglas Wilson2021-01-171-0/+2
| | | | | | | | I've never observed this counter taking a non-zero value, however I do think it's existence is justified by the comment in grab_local_todo_block. I've not added it to RTSStats in GHC.Stats, as it doesn't seem worth the api churn.
* rts: remove no_work counterDouglas Wilson2021-01-171-3/+0
| | | | We are no longer busyish waiting, so this is no longer meaningful
* rts/eventlog: Introduce event to demarcate new ticky sampleBen Gamari2021-01-171-1/+2
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* rts: Zero shrunk array slop in vanilla RTSBen Gamari2021-01-071-1/+5
| | | | | | But only when profiling or DEBUG are enabled. Fixes #17572.
* rts: Use weaker cas in WSDequeDouglas Wilson2020-12-191-0/+24
| | | | | | | | The algorithm described in the referenced paper uses this slightly weaker atomic op. This is the first "exotic" cas we're using. I've added a macro in the <ORDERING>_OP style to match existing ones.
* ThreadPaused: Don't zero slop until free vars are pushedGHC GitLab CI2020-11-291-0/+4
| | | | | | | | When threadPaused blackholes a thunk it calls `OVERWRITING_CLOSURE` to zero the slop for the benefit of the sanity checker. Previously this was done *before* pushing the thunk's free variables to the update remembered set. Consequently we would pull zero'd pointers to the update remembered set.
* rts: Use RTS_LIKELY in CHECKBen Gamari2020-11-261-2/+2
| | | | | Most compilers probably already infer that `barf` diverges but it nevertheless doesn't hurt to be explicit.
* RTS: Fix failed inlining of copy_tag.Andreas Klebinger2020-11-261-1/+6
| | | | | | | | | | | | | | | On windows using gcc-10 gcc failed to inline copy_tag into evacuate. To fix this we now set the always_inline attribute for the various copy* functions in Evac.c. The main motivation here is not the overhead of the function call, but rather that this allows the code to "specialize" for the size of the closure we copy which is often known at compile time. An earlier commit also tried to avoid evacuate_large inlining. But didn't quite succeed. So I also marked evacuate_large as noinline. Fixes #12416
* rts: Flush eventlog buffers from flushEventLogBen Gamari2020-11-242-2/+8
| | | | | | | | | | | | As noted in #18043, flushTrace failed flush anything beyond the writer. This means that a significant amount of data sitting in capability-local event buffers may never get flushed, despite the users' pleads for us to flush. Fix this by making flushEventLog flush all of the event buffers before flushing the writer. Fixes #18043.
* rts: Post ticky entry counts to the eventlogBen Gamari2020-11-212-1/+5
| | | | | | | | We currently only post the entry counters, not the other global counters as in my experience the former are more useful. We use the heap profiler's census period to decide when to dump. Also spruces up the documentation surrounding ticky-ticky a bit.
* AArch64/arm64 adjustmentsMoritz Angermann2020-11-153-3/+4
| | | | | | | | This addes the necessary logic to support aarch64 on elf, as well as aarch64 on mach-o, which Apple calls arm64. We change architecture name to AArch64, which is the official arm naming scheme.
* Add rts_listThreads and rts_listMiscRoots to RtsAPI.hDavid Eichmann2020-11-131-0/+12
| | | | | | | | These are used to find the current roots of the garbage collector. Co-authored-by: Sven Tennie's avatarSven Tennie <sven.tennie@gmail.com> Co-authored-by: Matthew Pickering's avatarMatthew Pickering <matthewtpickering@gmail.com> Co-authored-by: default avatarBen Gamari <bgamari.foss@gmail.com>
* rts: Introduce highMemDynamicGHC GitLab CI2020-11-111-0/+4
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* Add loadNativeObj and unloadNativeObjRay Shih2020-11-111-0/+13
| | | | | | | | | | | | | | | | | | | (This change is originally written by niteria) This adds two functions: * `loadNativeObj` * `unloadNativeObj` and implements them for Linux. They are useful if you want to load a shared object with Haskell code using the system linker and have GHC call dlclose() after the code is no longer referenced from the heap. Using the system linker allows you to load the shared object above outside the low-mem region. It also loads the DWARF sections in a way that `perf` understands. `dl_iterate_phdr` is what makes this implementation Linux specific.
* Add code comments for StgInfoTable and StgStack structsDavid Eichmann2020-11-102-2/+19
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* ghc-heap: expose decoding from heap representationDavid Eichmann2020-11-101-0/+9
| | | | | | Co-authored-by: Sven Tennie <sven.tennie@gmail.com> Co-authored-by: Matthew Pickering <matthewtpickering@gmail.com> Co-authored-by: Ben Gamari <bgamari.foss@gmail.com>
* Merge remote-tracking branch 'origin/wip/tsan/all'Ben Gamari2020-11-089-35/+186
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| * Merge branch 'wip/tsan/stm' into wip/tsan/allBen Gamari2020-11-011-3/+3
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| | * rts/stm: Strengthen orderings to SEQ_CST instead of volatilewip/tsan/stmBen Gamari2020-10-241-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Previously the `current_value`, `first_watch_queue_entry`, and `num_updates` fields of `StgTVar` were marked as `volatile` in an attempt to provide strong ordering. Of course, this isn't sufficient. We now use proper atomic operations. In most of these cases I strengthen the ordering all the way to SEQ_CST although it's possible that some could be weakened with some thought.
| * | Merge branch 'wip/tsan/wsdeque' into wip/tsan/allBen Gamari2020-11-011-0/+15
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| | * | rts/WSDeque: Rewrite with proper atomicswip/tsan/wsdequeBen Gamari2020-10-241-0/+15
| | |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | After a few attempts at shoring up the previous implementation, I ended up turning to the literature and now use the proven implementation, > N.M. Lê, A. Pop, A.Cohen, and F.Z. Nardelli. "Correct and Efficient > Work-Stealing for Weak Memory Models". PPoPP'13, February 2013, > ACM 978-1-4503-1922/13/02. Note only is this approach formally proven correct under C11 semantics but it is also proved to be a bit faster in practice.
| * | Merge branch 'wip/tsan/storage' into wip/tsan/allBen Gamari2020-11-015-15/+16
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| | * | rts: Use relaxed ordering on spinlock counterswip/tsan/storageBen Gamari2020-10-301-0/+2
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| | * | rts/SpinLock: Separate out slow pathBen Gamari2020-10-301-10/+5
| | | | | | | | | | | | | | | | | | | | | | | | Not only is this in general a good idea, but it turns out that GCC unrolls the retry loop, resulting is massive code bloat in critical parts of the RTS (e.g. `evacuate`).
| | * | rts: Join to concurrent mark thread during shutdownBen Gamari2020-10-301-1/+2
| | | | | | | | | | | | | | | | | | | | Previously we would take all capabilities but fail to join on the thread itself, potentially resulting in a leaked thread.
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