1. 30 Jan, 2013 1 commit
  2. 16 Jan, 2013 1 commit
  3. 24 Sep, 2012 1 commit
    • Simon Marlow's avatar
      Another overhaul of the recent_activity / idle GC handling (#5991) · 0b79d5cd
      Simon Marlow authored
      Improvements:
      
       - we now turn off the timer signal in the non-threaded RTS after
         idleGCDelay.  This should make the xmonad users on #5991 happy.
      
       - we now turn off the timer signal after idleGCDelay even if the
         idle GC is disabled with +RTS -I0.
      
       - we now do *not* turn off the timer when profiling.
      
       - more comments to explain the meaning of the various ACTIVITY_*
         values
      0b79d5cd
  4. 13 Dec, 2011 1 commit
  5. 11 Apr, 2011 1 commit
    • Simon Marlow's avatar
      Refactoring and tidy up · 1fb38442
      Simon Marlow authored
      This is a port of some of the changes from my private local-GC branch
      (which is still in darcs, I haven't converted it to git yet).  There
      are a couple of small functional differences in the GC stats: first,
      per-thread GC timings should now be more accurate, and secondly we now
      report average and maximum pause times. e.g. from minimax +RTS -N8 -s:
      
                                          Tot time (elapsed)  Avg pause  Max pause
        Gen  0      2755 colls,  2754 par   13.16s    0.93s     0.0003s    0.0150s
        Gen  1       769 colls,   769 par    3.71s    0.26s     0.0003s    0.0059s
      1fb38442
  6. 15 Dec, 2010 1 commit
    • Simon Marlow's avatar
      Implement stack chunks and separate TSO/STACK objects · f30d5273
      Simon Marlow authored
      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.
      f30d5273
  7. 17 Jun, 2010 1 commit
  8. 06 Apr, 2010 1 commit
  9. 29 Mar, 2010 2 commits
    • Simon Marlow's avatar
      Move a thread to the front of the run queue when another thread blocks on it · 2726a2f1
      Simon Marlow authored
      This fixes #3838, and was made possible by the new BLACKHOLE
      infrastructure.  To allow reording of the run queue I had to make it
      doubly-linked, which entails some extra trickiness with regard to
      GC write barriers and suchlike.
      2726a2f1
    • Simon Marlow's avatar
      New implementation of BLACKHOLEs · 5d52d9b6
      Simon Marlow authored
      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.
      5d52d9b6
  10. 01 Apr, 2010 1 commit
  11. 11 Mar, 2010 1 commit
    • Simon Marlow's avatar
      Use message-passing to implement throwTo in the RTS · 7408b392
      Simon Marlow authored
      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.
      7408b392
  12. 09 Mar, 2010 1 commit
    • Simon Marlow's avatar
      Split part of the Task struct into a separate struct InCall · 7effbbbb
      Simon Marlow authored
      The idea is that this leaves Tasks and OSThread in one-to-one
      correspondence.  The part of a Task that represents a call into
      Haskell from C is split into a separate struct InCall, pointed to by
      the Task and the TSO bound to it.  A given OSThread/Task thus always
      uses the same mutex and condition variable, rather than getting a new
      one for each callback.  Conceptually it is simpler, although there are
      more types and indirections in a few places now.
      
      This improves callback performance by removing some of the locks that
      we had to take when making in-calls.  Now we also keep the current Task
      in a thread-local variable if supported by the OS and gcc (currently
      only Linux).
      7effbbbb
  13. 12 Dec, 2009 1 commit
    • chak@cse.unsw.edu.au.'s avatar
      Expose all EventLog events as DTrace probes · 015d3d46
      chak@cse.unsw.edu.au. authored
      - Defines a DTrace provider, called 'HaskellEvent', that provides a probe
        for every event of the eventlog framework.
      - In contrast to the original eventlog, the DTrace probes are available in
        all flavours of the runtime system (DTrace probes have virtually no
        overhead if not enabled); when -DTRACING is defined both the regular
        event log as well as DTrace probes can be used.
      - Currently, Mac OS X only.  User-space DTrace probes are implemented
        differently on Mac OS X than in the original DTrace implementation.
        Nevertheless, it shouldn't be too hard to enable these probes on other
        platforms, too.
      - Documentation is at http://hackage.haskell.org/trac/ghc/wiki/DTrace
      015d3d46
  14. 08 Oct, 2009 1 commit
  15. 09 Sep, 2009 1 commit
  16. 29 Aug, 2009 1 commit
    • Simon Marlow's avatar
      Unify event logging and debug tracing. · a5288c55
      Simon Marlow authored
        - tracing facilities are now enabled with -DTRACING, and -DDEBUG
          additionally enables debug-tracing.  -DEVENTLOG has been
          removed.
      
        - -debug now implies -eventlog
      
        - events can be printed to stderr instead of being sent to the
          binary .eventlog file by adding +RTS -v (which is implied by the
          +RTS -Dx options).
      
        - -Dx debug messages can be sent to the binary .eventlog file
          by adding +RTS -l.  This should help debugging by reducing
          the impact of debug tracing on execution time.
      
        - Various debug messages that duplicated the information in events
          have been removed.
      a5288c55
  17. 05 Aug, 2009 1 commit
  18. 02 Aug, 2009 1 commit
    • Simon Marlow's avatar
      RTS tidyup sweep, first phase · a2a67cd5
      Simon Marlow authored
      The first phase of this tidyup is focussed on the header files, and in
      particular making sure we are exposinng publicly exactly what we need
      to, and no more.
      
       - Rts.h now includes everything that the RTS exposes publicly,
         rather than a random subset of it.
      
       - Most of the public header files have moved into subdirectories, and
         many of them have been renamed.  But clients should not need to
         include any of the other headers directly, just #include the main
         public headers: Rts.h, HsFFI.h, RtsAPI.h.
      
       - All the headers needed for via-C compilation have moved into the
         stg subdirectory, which is self-contained.  Most of the headers for
         the rest of the RTS APIs have moved into the rts subdirectory.
      
       - I left MachDeps.h where it is, because it is so widely used in
         Haskell code.
       
       - I left a deprecated stub for RtsFlags.h in place.  The flag
         structures are now exposed by Rts.h.
      
       - Various internal APIs are no longer exposed by public header files.
      
       - Various bits of dead code and declarations have been removed
      
       - More gcc warnings are turned on, and the RTS code is more
         warning-clean.
      
       - More source files #include "PosixSource.h", and hence only use
         standard POSIX (1003.1c-1995) interfaces.
      
      There is a lot more tidying up still to do, this is just the first
      pass.  I also intend to standardise the names for external RTS APIs
      (e.g use the rts_ prefix consistently), and declare the internal APIs
      as hidden for shared libraries.
      a2a67cd5
  19. 02 Jun, 2009 1 commit
  20. 17 Mar, 2009 1 commit
    • Simon Marlow's avatar
      Add fast event logging · 8b18faef
      Simon Marlow authored
      Generate binary log files from the RTS containing a log of runtime
      events with timestamps.  The log file can be visualised in various
      ways, for investigating runtime behaviour and debugging performance
      problems.  See for example the forthcoming ThreadScope viewer.
      
      New GHC option:
      
        -eventlog   (link-time option) Enables event logging.
      
        +RTS -l     (runtime option) Generates <prog>.eventlog with
                    the binary event information.
      
      This replaces some of the tracing machinery we already had in the RTS:
      e.g. +RTS -vg  for GC tracing (we should do this using the new event
      logging instead).
      
      Event logging has almost no runtime cost when it isn't enabled, though
      in the future we might add more fine-grained events and this might
      change; hence having a link-time option and compiling a separate
      version of the RTS for event logging.  There's a small runtime cost
      for enabling event-logging, for most programs it shouldn't make much
      difference.
      
      (Todo: docs)
      8b18faef
  21. 09 Dec, 2008 1 commit
  22. 13 Nov, 2008 1 commit
    • Simon Marlow's avatar
      Fix an extremely subtle deadlock bug on x86_64 · 6d316585
      Simon Marlow authored
      The recent_activity flag was an unsigned int, but we sometimes do a
      64-bit xchg() on it, which overwrites the next word in memory.  This
      happened to contain the sched_state flag, which is used to control the
      orderly shutdown of the system.  If the xchg() happened during
      shutdown, the scheduler would get confused and deadlock.  Don't you
      just love C?
      6d316585
  23. 19 Sep, 2008 1 commit
  24. 11 Sep, 2008 1 commit
  25. 09 Sep, 2008 1 commit
    • Simon Marlow's avatar
      Fix race condition in wakeupThreadOnCapability() (#2574) · d572aed6
      Simon Marlow authored
      wakeupThreadOnCapbility() is used to signal another capability that
      there is a thread waiting to be added to its run queue.  It adds the
      thread to the (locked) wakeup queue on the remote capability.  In
      order to do this, it has to modify the TSO's link field, which has a
      write barrier.  The write barrier might put the TSO on the mutable
      list, and the bug was that it was using the mutable list of the
      *target* capability, which we do not have exclusive access to.  We
      should be using the current Capabilty's mutable list in this case.
      d572aed6
  26. 16 Apr, 2008 3 commits
  27. 30 Oct, 2007 1 commit
  28. 24 Jul, 2007 1 commit
    • Simon Marlow's avatar
      hs_exit()/shutdownHaskell(): wait for outstanding foreign calls to complete before returning · 681aad99
      Simon Marlow authored
      This is pertinent to #1177.  When shutting down a DLL, we need to be
      sure that there are no OS threads that can return to the code that we
      are about to unload, and previously the threaded RTS was unsafe in
      this respect.
      
      When exiting a standalone program we don't have to be quite so
      paranoid: all the code will disappear at the same time as any running
      threads.  Happily exiting a program happens via a different path:
      shutdownHaskellAndExit().  If we're about to exit(), then there's no
      need to wait for foreign calls to complete.
      681aad99
  29. 11 Dec, 2006 1 commit
    • Ian Lynagh's avatar
      Add freeScheduler/freeTaskManager and call it later than exitScheduler · cf6b495d
      Ian Lynagh authored
      We were freeing the tasks in exitScheduler (stopTaskManager) before
      exitStorage (stat_exit), but the latter needs to walk down the list
      printing stats. Resulted in segfaults with commands like
          ghc -v0 -e main q.hs -H32m -H32m +RTS -Sstderr
      (where q.hs is trivial), but very sensitive to exact commandline and
      libc version or something.
      cf6b495d
  30. 24 Oct, 2006 1 commit
    • Simon Marlow's avatar
      Split GC.c, and move storage manager into sm/ directory · ab0e778c
      Simon Marlow authored
      In preparation for parallel GC, split up the monolithic GC.c file into
      smaller parts.  Also in this patch (and difficult to separate,
      unfortunatley):
        
        - Don't include Stable.h in Rts.h, instead just include it where
          necessary.
        
        - consistently use STATIC_INLINE in source files, and INLINE_HEADER
          in header files.  STATIC_INLINE is now turned off when DEBUG is on,
          to make debugging easier.
        
        - The GC no longer takes the get_roots function as an argument.
          We weren't making use of this generalisation.
      ab0e778c
  31. 16 Jun, 2006 1 commit
    • Simon Marlow's avatar
      Asynchronous exception support for SMP · b1953bbb
      Simon Marlow authored
      This patch makes throwTo work with -threaded, and also refactors large
      parts of the concurrency support in the RTS to clean things up.  We
      have some new files:
      
        RaiseAsync.{c,h}	asynchronous exception support
        Threads.{c,h}         general threading-related utils
      
      Some of the contents of these new files used to be in Schedule.c,
      which is smaller and cleaner as a result of the split.
      
      Asynchronous exception support in the presence of multiple running
      Haskell threads is rather tricky.  In fact, to my annoyance there are
      still one or two bugs to track down, but the majority of the tests run
      now.
      b1953bbb
  32. 08 Jun, 2006 2 commits
    • Simon Marlow's avatar
      fix possible ^C problems · 7434fb5b
      Simon Marlow authored
      Calling prodAllCapabilities() from interruptStgRts() was wrong, for
      the same reasons that we stopped doing it in handle_tick().  We now
      use the same mechanism (send a byte down the pipe to the IO manager
      thread), but abstract it in a wakeUpRts() function in the scheduler.
      7434fb5b
    • Simon Marlow's avatar
      New tracing interface · 5a2769f0
      Simon Marlow authored
      A simple interface for generating trace messages with timestamps and
      thread IDs attached to them.  Most debugging output goes through this
      interface now, so it is straightforward to get timestamped debugging
      traces with +RTS -vt.  Also, we plan to use this to generate
      parallelism profiles from the trace output.
      5a2769f0
  33. 07 Jun, 2006 1 commit
  34. 07 Apr, 2006 1 commit
    • Simon Marlow's avatar
      Reorganisation of the source tree · 0065d5ab
      Simon Marlow authored
      Most of the other users of the fptools build system have migrated to
      Cabal, and with the move to darcs we can now flatten the source tree
      without losing history, so here goes.
      
      The main change is that the ghc/ subdir is gone, and most of what it
      contained is now at the top level.  The build system now makes no
      pretense at being multi-project, it is just the GHC build system.
      
      No doubt this will break many things, and there will be a period of
      instability while we fix the dependencies.  A straightforward build
      should work, but I haven't yet fixed binary/source distributions.
      Changes to the Building Guide will follow, too.
      0065d5ab
  35. 27 Mar, 2006 1 commit
    • Simon Marlow's avatar
      Add a new primitive forkOn#, for forking a thread on a specific Capability · c520a3a2
      Simon Marlow authored
      This gives some control over affinity, while we figure out the best
      way to automatically schedule threads to make best use of the
      available parallelism.
      
      In addition to the primitive, there is also:
       
        GHC.Conc.forkOnIO :: Int -> IO () -> IO ThreadId
      
      where 'forkOnIO i m' creates a thread on Capability (i `rem` N), where
      N is the number of available Capabilities set by +RTS -N.
      
      Threads forked by forkOnIO do not automatically migrate when there are
      free Capabilities, like normal threads do.  Still, if you're using
      forkOnIO exclusively, it's a good idea to do +RTS -qm to disable work
      pushing anyway (work pushing takes too much time when the run queues
      are large, this is something we need to fix).
      c520a3a2
  36. 24 Mar, 2006 1 commit
    • Simon Marlow's avatar
      Add some more flexibility to the multiproc scheduler · 4368121d
      Simon Marlow authored
      There are two new options in the -threaded RTS:
       
        -qm       Don't automatically migrate threads between CPUs
        -qw       Migrate a thread to the current CPU when it is woken up
      
      previously both of these were effectively off, i.e. threads were
      migrated between CPUs willy-milly, and threads were always migrated to
      the current CPU when woken up.  This is the first step in tweaking the
      scheduling for more effective work balancing, there will no doubt be
      more to come.
      4368121d