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* Fix note references and some typosGabor Greif2017-07-261-1/+1
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* Prefer #if defined to #ifdefBen Gamari2017-04-281-32/+32
| | | | Our new CPP linter enforces this.
* Typecast covers entire expression to fix format warning.bollu2017-02-141-10/+15
| | | | | | | | | | | | | | - Fixes (#12636). - changes all the typecasts to _unsinged long long_ to have the format specifiers work. Reviewers: austin, bgamari, erikd, simonmar, Phyx Reviewed By: erikd, Phyx Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D3129
* Use C99's boolBen Gamari2016-11-291-38/+38
| | | | | | | | | | | | Test Plan: Validate on lots of platforms Reviewers: erikd, simonmar, austin Reviewed By: erikd, simonmar Subscribers: michalt, thomie Differential Revision: https://phabricator.haskell.org/D2699
* Remove CONSTR_STATICSimon Marlow2016-11-141-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: We currently have two info tables for a constructor * XXX_con_info: the info table for a heap-resident instance of the constructor, It has type CONSTR, or one of the specialised types like CONSTR_1_0 * XXX_static_info: the info table for a static instance of this constructor, which has type CONSTR_STATIC or CONSTR_STATIC_NOCAF. I'm getting rid of the latter, and using the `con_info` info table for both static and dynamic constructors. For rationale and more details see Note [static constructors] in SMRep.hs. I also removed these macros: `isSTATIC()`, `ip_STATIC()`, `closure_STATIC()`, since they relied on the CONSTR/CONSTR_STATIC distinction, and anyway HEAP_ALLOCED() does the same job. Test Plan: validate Reviewers: bgamari, simonpj, austin, gcampax, hvr, niteria, erikd Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2690 GHC Trac Issues: #12455
* rts: Disable -hb with multiple capabilitiesBen Gamari2016-09-121-0/+7
| | | | | | | | | | | | | | | | | Biographical profiling is not thread-safe as documented in #12019. Throw an error when it is used in this way. Test Plan: Validate Reviewers: simonmar, austin, erikd Reviewed By: erikd Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2516 GHC Trac Issues: #12019
* Compact RegionsGiovanni Campagna2016-07-201-0/+23
| | | | | | | | | | | | | | | | | | | | | | | | | | This brings in initial support for compact regions, as described in the ICFP 2015 paper "Efficient Communication and Collection with Compact Normal Forms" (Edward Z. Yang et.al.) and implemented by Giovanni Campagna. Some things may change before the 8.2 release, but I (Simon M.) wanted to get the main patch committed so that we can iterate. What documentation there is is in the Data.Compact module in the new compact package. We'll need to extend and polish the documentation before the release. Test Plan: validate (new test cases included) Reviewers: ezyang, simonmar, hvr, bgamari, austin Subscribers: vikraman, Yuras, RyanGlScott, qnikst, mboes, facundominguez, rrnewton, thomie, erikd Differential Revision: https://phabricator.haskell.org/D1264 GHC Trac Issues: #11493
* Log heap profiler samples to event logBen Gamari2016-07-161-3/+29
| | | | | | | | | | | | Test Plan: Try it Reviewers: hvr, simonmar, austin, erikd Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D1722 GHC Trac Issues: #11094
* NUMA supportSimon Marlow2016-06-101-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: The aim here is to reduce the number of remote memory accesses on systems with a NUMA memory architecture, typically multi-socket servers. Linux provides a NUMA API for doing two things: * Allocating memory local to a particular node * Binding a thread to a particular node When given the +RTS --numa flag, the runtime will * Determine the number of NUMA nodes (N) by querying the OS * Assign capabilities to nodes, so cap C is on node C%N * Bind worker threads on a capability to the correct node * Keep a separate free lists in the block layer for each node * Allocate the nursery for a capability from node-local memory * Allocate blocks in the GC from node-local memory For example, using nofib/parallel/queens on a 24-core 2-socket machine: ``` $ ./Main 15 +RTS -N24 -s -A64m Total time 173.960s ( 7.467s elapsed) $ ./Main 15 +RTS -N24 -s -A64m --numa Total time 150.836s ( 6.423s elapsed) ``` The biggest win here is expected to be allocating from node-local memory, so that means programs using a large -A value (as here). According to perf, on this program the number of remote memory accesses were reduced by more than 50% by using `--numa`. Test Plan: * validate * There's a new flag --debug-numa=<n> that pretends to do NUMA without actually making the OS calls, which is useful for testing the code on non-NUMA systems. * TODO: I need to add some unit tests Reviewers: erikd, austin, rwbarton, ezyang, bgamari, hvr, niteria Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2199
* rts: More const correct-ness fixesErik de Castro Lopo2016-05-181-9/+9
| | | | | | | | | | | | | | | | | | | | In addition to more const-correctness fixes this patch fixes an infelicity of the previous const-correctness patch (995cf0f356) which left `UNTAG_CLOSURE` taking a `const StgClosure` pointer parameter but returning a non-const pointer. Here we restore the original type signature of `UNTAG_CLOSURE` and add a new function `UNTAG_CONST_CLOSURE` which takes and returns a const `StgClosure` pointer and uses that wherever possible. Test Plan: Validate on Linux, OS X and Windows Reviewers: Phyx, hsyl20, bgamari, austin, simonmar, trofi Reviewed By: simonmar, trofi Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2231
* rts: Make function pointer parameters `const` where possibleErik de Castro Lopo2016-05-121-4/+4
| | | | | | | | | | | | | | | | If a function takes a pointer parameter and doesn't update what the pointer points to, we can add `const` to the parameter declaration to document that no updates occur. Test Plan: Validate on Linux, OS X and Windows Reviewers: austin, Phyx, bgamari, simonmar, hsyl20 Reviewed By: bgamari, simonmar, hsyl20 Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2200
* Use stdint types for Stg{Word,Int}{8,16,32,64}Tomas Carnecky2016-05-101-1/+1
| | | | | | | | | | | | | | | | | | We can't define Stg{Int,Word} in terms of {,u}intptr_t because STG depends on them being the exact same size as void*, and {,u}intptr_t does not make that guarantee. Furthermore, we also need to define StgHalf{Int,Word}, so the preprocessor if needs to stay. But we can at least keep it in a single place instead of repeating it in various files. Also define STG_{INT,WORD}{8,16,32,64}_{MIN,MAX} and use it in HsFFI.h, further reducing the need for CPP in other files. Reviewers: austin, bgamari, simonmar, hvr, erikd Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2182
* rts/ProfHeap.c: Use `ssize_t` instead of `long`.Erik de Castro Lopo2016-05-081-21/+22
| | | | | | | | | | | | | | | On x64 Windows `sizeof long` is 4 which could easily overflow resulting in incorrect heap profiling results. This change does not affect either Linux or OS X where `sizeof long` == `sizeof ssize_t` regardless of machine word size. Test Plan: Validate on Linux and Windows Reviewers: hsyl20, bgamari, simonmar, austin Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2177
* rts: Replace `nat` with `uint32_t`Erik de Castro Lopo2016-05-051-15/+15
| | | | | | | | | | | | The `nat` type was an alias for `unsigned int` with a comment saying it was at least 32 bits. We keep the typedef in case client code is using it but mark it as deprecated. Test Plan: Validated on Linux, OS X and Windows Reviewers: simonmar, austin, thomie, hvr, bgamari, hsyl20 Differential Revision: https://phabricator.haskell.org/D2166
* prof: Fix heap census for large ARR_WORDS (#11627)Jason Eisenberg2016-03-201-0/+14
| | | | | | | | | | | | | | | | | The heap census now handles large ARR_WORDS objects which have been shrunk by shrinkMutableByteArray# or resizeMutableByteArray#. Test Plan: ./validate && make test WAY=profasm Reviewers: hvr, bgamari, austin, thomie Reviewed By: thomie Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2005 GHC Trac Issues: #11627
* Fix the Windows buildThomas Miedema2016-01-291-1/+1
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* Fix segmentation fault when .prof file not writeableThomas Miedema2016-01-261-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | There are two ways to do retainer profiling. Quoting from the user's guide: 1. `+RTS -hr` "Breaks down the graph by retainer set" 2. `+RTS -hr<cc> -h<x>`, where `-h<x>` is one of normal heap profiling break-down options (e.g. `-hc`), and `-hr<cc> means "Restrict the profile to closures with retainer sets containing cost-centre stacks with one of the specified cost centres at the top." Retainer profiling writes to a .hp file, like the other heap profiling options, but also to a .prof file. Therefore, when the .prof file is not writeable for whatever reason, retainer profiling should be turned off completely. This worked ok when running the program with `+RTS -hr` (option 1), but a segfault would occur when using `+RTS -hr<cc> -h<x>`, with `x!=r` (option 2). This commit fixes that. Reviewed by: bgamari Differential Revision: https://phabricator.haskell.org/D1849 GHC Trac Issues: #11489
* Remove unused IND_PERMJoachim Breitner2016-01-231-1/+0
| | | | | | | | | | | | | | | | | it seems that this closure type has not been in use since 5d52d9, so all this is dead and untested code. This removes it. Some of the code might be useful for a counting indirection as described in #10613, so when implementing that, have a look at what this commit removes. Test Plan: validate on harbormaster Reviewers: austin, bgamari, simonmar Reviewed By: simonmar Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D1821
* Fix +RTS -h when compiling without -profSimon Marlow2016-01-081-5/+1
| | | | | | | | | | | | | | | | Summary: Was broken by ce1f1607ed7f8fedd2f63c8610cafefd59baaf32. I've added a test so that hopefully it won't break again. Test Plan: validate & new test case Reviewers: bgamari, austin, erikd Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D1746 GHC Trac Issues: #11304
* RtsFlags: Fix const warningBen Gamari2015-11-211-2/+2
| | | | | | | | | | Reviewers: austin Reviewed By: austin Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D1509
* Make GHCi & TH work when the compiler is built with -profSimon Marlow2015-11-071-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: Amazingly, there were zero changes to the byte code generator and very few changes to the interpreter - mainly because we've used good abstractions that hide the differences between profiling and non-profiling. So that bit was pleasantly straightforward, but there were a pile of other wibbles to get the whole test suite through. Note that a compiler built with -prof is now like one built with -dynamic, in that to use TH you have to build the code the same way. For dynamic, we automatically enable -dynamic-too when TH is required, but we don't have anything equivalent for profiling, so you have to explicitly use -prof when building code that uses TH with a profiled compiler. For this reason Cabal won't work with TH. We don't expect to ship a profiled compiler, so I think that's OK. Test Plan: validate with GhcProfiled=YES in validate.mk Reviewers: goldfire, bgamari, rwbarton, austin, hvr, erikd, ezyang Reviewed By: ezyang Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D1407 GHC Trac Issues: #4837, #545
* s/StgArrWords/StgArrBytes/Siddhanathan Shanmugam2015-09-111-1/+1
| | | | | | | | | | Rename StgArrWords to StgArrBytes (see Trac #8552) Reviewed By: austin Differential Revision: https://phabricator.haskell.org/D1233 GHC Trac Issues: #8552
* rts: add "-no-rtsopts-suggestions" optionJavran Cheng2015-05-061-6/+8
| | | | | | | | | | | | | | | | | | Depends on D767 Setting this flag prevents RTS from giving RTS suggestions like "Use `+RTS -Ksize -RTS' to increase it." According to the comment @rwbarton made in #9579, sometimes "+RTS" suggestions don't make sense (e.g. when the program is precompiled and installed through package managers), we can encourage people to distribute binaries with either "-no-rtsopts-suggestions" or "-rtsopts". Reviewed By: erikd, austin Differential Revision: https://phabricator.haskell.org/D809 GHC Trac Issues: #9579
* Better hints when RTS options not available (Trac #9579)Javran Cheng2015-04-171-1/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch provides user with a better hint when most RTS options are not available (not compiled with `-rtsopts`). A new field "rtsOptsEnabled" is added into RtsFlags.MiscFlags to tell the availablity of RTS options. Some concerns: * Unlike other flag fields in "libraries/base/GHC/RTS/Flags.hsc", "RtsOptsEnabled" is defined in "includes/RtsAPI.h" and lacks constant macros. Therefore In "GHC.RTS", "RtsOptsEnabled" simply derives Enum instance and reads as of type "CInt". * There are other ways to change RTS options (e.g. `-with-rtsopts`), but it might be too verbose to mention. Test Plan: validate Reviewers: austin, hvr, thomie, simonmar Reviewed By: thomie Subscribers: thomie, rwbarton Differential Revision: https://phabricator.haskell.org/D767 GHC Trac Issues: #9579
* Give full-precision time for BEGIN_SAMPLE/END_SAMPLE.Edward Z. Yang2015-03-021-4/+2
| | | | | | | | | | | | Summary: Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu> Test Plan: validate Reviewers: simonmar, austin Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D679
* [skip ci] rts: Detabify ProfHeap.cAustin Seipp2014-10-211-451/+450
| | | | Signed-off-by: Austin Seipp <austin@well-typed.com>
* Revert "rts: add Emacs 'Local Variables' to every .c file"Simon Marlow2014-09-291-8/+0
| | | | This reverts commit 39b5c1cbd8950755de400933cecca7b8deb4ffcd.
* rts: add Emacs 'Local Variables' to every .c fileAustin Seipp2014-07-281-0/+8
| | | | | | | | This will hopefully help ensure some basic consistency in the forward by overriding buffer variables. In particular, it sets the wrap length, the offset to 4, and turns off tabs. Signed-off-by: Austin Seipp <austin@well-typed.com>
* rts: Fix potential memory leak in ProfHeap.cAustin Seipp2014-04-271-3/+4
| | | | | | Discovered by Coverity. CID 43166. Signed-off-by: Austin Seipp <austin@well-typed.com>
* Add SmallArray# and SmallMutableArray# typesJohan Tibell2014-03-291-0/+8
| | | | | | | | | | | | | | | These array types are smaller than Array# and MutableArray# and are faster when the array size is small, as they don't have the overhead of a card table. Having no card table reduces the closure size with 2 words in the typical small array case and leads to less work when updating or GC:ing the array. Reduces both the runtime and memory allocation by 8.8% on my insert benchmark for the HashMap type in the unordered-containers package, which makes use of lots of small arrays. With tuned GC settings (i.e. `+RTS -A6M`) the runtime reduction is 15%. Fixes #8923.
* fix a small memory leak with +RTS -hbSimon Marlow2013-11-141-10/+9
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* Heap profiling: flush .hp file at the end of each frameTakano Akio2013-03-251-0/+3
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* Typofix.Edward Z. Yang2013-03-021-1/+1
| | | | Signed-off-by: Edward Z. Yang <ezyang@mit.edu>
* Add a write barrier for TVAR closuresSimon Marlow2012-11-161-1/+2
| | | | | | | | | | This improves GC performance when there are a lot of TVars in the heap. For instance, a TChan with a lot of elements causes a massive GC drag without this patch. There's more to do - several other STM closure types don't have write barriers, so GC performance when there are a lot of threads blocked on STM isn't great. But fixing the problem for TVar is a good start.
* Deprecate lnat, and use StgWord insteadSimon Marlow2012-09-071-1/+1
| | | | | | | | | | | | lnat was originally "long unsigned int" but we were using it when we wanted a 64-bit type on a 64-bit machine. This broke on Windows x64, where long == int == 32 bits. Using types of unspecified size is bad, but what we really wanted was a type with N bits on an N-bit machine. StgWord is exactly that. lnat was mentioned in some APIs that clients might be using (e.g. StackOverflowHook()), so we leave it defined but with a comment to say that it's deprecated.
* Fix warnings on Win64Ian Lynagh2012-04-261-1/+1
| | | | | | Mostly this meant getting pointer<->int conversions to use the right sizes. lnat is now size_t, rather than unsigned long, as that seems a better match for how it's used.
* Turn a bunch of ints into longs to avoid overflow (#5656)Simon Marlow2011-11-301-18/+18
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* Time handling overhaulSimon Marlow2011-11-251-2/+1
| | | | | | | | | | | | | | | | | | | | | Terminology cleanup: the type "Ticks" has been renamed "Time", which is an StgWord64 in units of TIME_RESOLUTION (currently nanoseconds). The terminology "tick" is now used consistently to mean the interval between timer signals. The ticker now always ticks in realtime (actually CLOCK_MONOTONIC if we have it). Before it used CPU time in the non-threaded RTS and realtime in the threaded RTS, but I've discovered that the CPU timer has terrible resolution (at least on Linux) and isn't much use for profiling. So now we always use realtime. This should also fix The default tick interval is now 10ms, except when profiling where we drop it to 1ms. This gives more accurate profiles without affecting runtime too much (<1%). Lots of cleanups - the resolution of Time is now in one place only (Rts.h) rather than having calculations that depend on the resolution scattered all over the RTS. I hope I found them all.
* Overhaul of infrastructure for profiling, coverage (HPC) and breakpointsSimon Marlow2011-11-021-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | User visible changes ==================== Profilng -------- Flags renamed (the old ones are still accepted for now): OLD NEW --------- ------------ -auto-all -fprof-auto -auto -fprof-exported -caf-all -fprof-cafs New flags: -fprof-auto Annotates all bindings (not just top-level ones) with SCCs -fprof-top Annotates just top-level bindings with SCCs -fprof-exported Annotates just exported bindings with SCCs -fprof-no-count-entries Do not maintain entry counts when profiling (can make profiled code go faster; useful with heap profiling where entry counts are not used) Cost-centre stacks have a new semantics, which should in most cases result in more useful and intuitive profiles. If you find this not to be the case, please let me know. This is the area where I have been experimenting most, and the current solution is probably not the final version, however it does address all the outstanding bugs and seems to be better than GHC 7.2. Stack traces ------------ +RTS -xc now gives more information. If the exception originates from a CAF (as is common, because GHC tends to lift exceptions out to the top-level), then the RTS walks up the stack and reports the stack in the enclosing update frame(s). Result: +RTS -xc is much more useful now - but you still have to compile for profiling to get it. I've played around a little with adding 'head []' to GHC itself, and +RTS -xc does pinpoint the problem quite accurately. I plan to add more facilities for stack tracing (e.g. in GHCi) in the future. Coverage (HPC) -------------- * derived instances are now coloured yellow if they weren't used * likewise record field names * entry counts are more accurate (hpc --fun-entry-count) * tab width is now correct (markup was previously off in source with tabs) Internal changes ================ In Core, the Note constructor has been replaced by Tick (Tickish b) (Expr b) which is used to represent all the kinds of source annotation we support: profiling SCCs, HPC ticks, and GHCi breakpoints. Depending on the properties of the Tickish, different transformations apply to Tick. See CoreUtils.mkTick for details. Tickets ======= This commit closes the following tickets, test cases to follow: - Close #2552: not a bug, but the behaviour is now more intuitive (test is T2552) - Close #680 (test is T680) - Close #1531 (test is result001) - Close #949 (test is T949) - Close #2466: test case has bitrotted (doesn't compile against current version of vector-space package)
* Fix heap profiling timesIan Lynagh2011-07-241-2/+2
| | | | | | | | | | Now that the heap census runs in the middle of garbage collections, the "CPU time" it was calculating included any CPU time used so far in the current GC. This could cause CPU time to appear to go down, which means hp2ps complained about "samples out of sequence". I'm not sure if this is the nicest way to solve this (maybe resurrecting mut_user_time_during_GC would be better?) but it gets things working again.
* Better heap profiling for pinned objects (e.g. ByteStrings).Simon Marlow2011-07-011-83/+98
| | | | | | | | Previously we were completely ignoring these, due to the difficulties of traversing the pinned blocks (the objects are not necessarily end-to-end, we can't tell how large the gaps are). Now just count the whole block as a big ARR_WORDS, so at least we're accounting for the memory and it has the right type.
* Fix gcc 4.6 warnings; fixes #5176Ian Lynagh2011-06-251-9/+9
| | | | | | | | | | | Based on a patch from David Terei. Some parts are a little ugly (e.g. defining things that only ASSERTs use only when DEBUG is defined), so we might want to tweak things a little. I've also turned off -Werror for didn't-inline warnings, as we now get a few such warnings.
* heapCensus: we need to traverse the heap fragments stored in theSimon Marlow2011-05-091-1/+10
| | | | gen_workspace structures. Fixes heapprof001(prof_hc_hb).
* Make retainer profiling use the label length (-L) flag)Ian Lynagh2011-05-071-1/+1
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* Change the way module initialisation is done (#3252, #4417)Simon Marlow2011-04-121-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Previously the code generator generated small code fragments labelled with __stginit_M for each module M, and these performed whatever initialisation was necessary for that module and recursively invoked the initialisation functions for imported modules. This appraoch had drawbacks: - FFI users had to call hs_add_root() to ensure the correct initialisation routines were called. This is a non-standard, and ugly, API. - unless we were using -split-objs, the __stginit dependencies would entail linking the whole transitive closure of modules imported, whether they were actually used or not. In an extreme case (#4387, #4417), a module from GHC might be imported for use in Template Haskell or an annotation, and that would force the whole of GHC to be needlessly linked into the final executable. So now instead we do our initialisation with C functions marked with __attribute__((constructor)), which are automatically invoked at program startup time (or DSO load-time). The C initialisers are emitted into the stub.c file. This means that every time we compile with -prof or -hpc, we now get a stub file, but thanks to #3687 that is now invisible to the user. There are some refactorings in the RTS (particularly for HPC) to handle the fact that initialisers now get run earlier than they did before. The __stginit symbols are still generated, and the hs_add_root() function still exists (but does nothing), for backwards compatibility.
* Implement stack chunks and separate TSO/STACK objectsSimon Marlow2010-12-151-4/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch makes two changes to the way stacks are managed: 1. The stack is now stored in a separate object from the TSO. This means that it is easier to replace the stack object for a thread when the stack overflows or underflows; we don't have to leave behind the old TSO as an indirection any more. Consequently, we can remove ThreadRelocated and deRefTSO(), which were a pain. This is obviously the right thing, but the last time I tried to do it it made performance worse. This time I seem to have cracked it. 2. Stacks are now represented as a chain of chunks, rather than a single monolithic object. The big advantage here is that individual chunks are marked clean or dirty according to whether they contain pointers to the young generation, and the GC can avoid traversing clean stack chunks during a young-generation collection. This means that programs with deep stacks will see a big saving in GC overhead when using the default GC settings. A secondary advantage is that there is much less copying involved as the stack grows. Programs that quickly grow a deep stack will see big improvements. In some ways the implementation is simpler, as nothing special needs to be done to reclaim stack as the stack shrinks (the GC just recovers the dead stack chunks). On the other hand, we have to manage stack underflow between chunks, so there's a new stack frame (UNDERFLOW_FRAME), and we now have separate TSO and STACK objects. The total amount of code is probably about the same as before. There are new RTS flags: -ki<size> Sets the initial thread stack size (default 1k) Egs: -ki4k -ki2m -kc<size> Sets the stack chunk size (default 32k) -kb<size> Sets the stack chunk buffer size (default 1k) -ki was previously called just -k, and the old name is still accepted for backwards compatibility. These new options are documented.
* Remove the IND_OLDGEN and IND_OLDGEN_PERM closure typesSimon Marlow2010-04-011-2/+0
| | | | | | | These are no longer used: once upon a time they used to have different layout from IND and IND_PERM respectively, but that is no longer the case since we changed the remembered set to be an array of addresses instead of a linked list of closures.
* New implementation of BLACKHOLEsSimon Marlow2010-03-291-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This replaces the global blackhole_queue with a clever scheme that enables us to queue up blocked threads on the closure that they are blocked on, while still avoiding atomic instructions in the common case. Advantages: - gets rid of a locked global data structure and some tricky GC code (replacing it with some per-thread data structures and different tricky GC code :) - wakeups are more prompt: parallel/concurrent performance should benefit. I haven't seen anything dramatic in the parallel benchmarks so far, but a couple of threading benchmarks do improve a bit. - waking up a thread blocked on a blackhole is now O(1) (e.g. if it is the target of throwTo). - less sharing and better separation of Capabilities: communication is done with messages, the data structures are strictly owned by a Capability and cannot be modified except by sending messages. - this change will utlimately enable us to do more intelligent scheduling when threads block on each other. This is what started off the whole thing, but it isn't done yet (#3838). I'll be documenting all this on the wiki in due course.
* Use message-passing to implement throwTo in the RTSSimon Marlow2010-03-111-26/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | This replaces some complicated locking schemes with message-passing in the implementation of throwTo. The benefits are - previously it was impossible to guarantee that a throwTo from a thread running on one CPU to a thread running on another CPU would be noticed, and we had to rely on the GC to pick up these forgotten exceptions. This no longer happens. - the locking regime is simpler (though the code is about the same size) - threads can be unblocked from a blocked_exceptions queue without having to traverse the whole queue now. It's a rare case, but replaces an O(n) operation with an O(1). - generally we move in the direction of sharing less between Capabilities (aka HECs), which will become important with other changes we have planned. Also in this patch I replaced several STM-specific closure types with a generic MUT_PRIM closure type, which allowed a lot of code in the GC and other places to go away, hence the line-count reduction. The message-passing changes resulted in about a net zero line-count difference.
* GC refactoring, remove "steps"Simon Marlow2009-12-031-12/+6
| | | | | | | | | | | | | | | | | | | | | The GC had a two-level structure, G generations each of T steps. Steps are for aging within a generation, mostly to avoid premature promotion. Measurements show that more than 2 steps is almost never worthwhile, and 1 step is usually worse than 2. In theory fractional steps are possible, so the ideal number of steps is somewhere between 1 and 3. GHC's default has always been 2. We can implement 2 steps quite straightforwardly by having each block point to the generation to which objects in that block should be promoted, so blocks in the nursery point to generation 0, and blocks in gen 0 point to gen 1, and so on. This commit removes the explicit step structures, merging generations with steps, thus simplifying a lot of code. Performance is unaffected. The tunable number of steps is now gone, although it may be replaced in the future by a way to tune the aging in generation 0.
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