[commit: ghc] master: Run C finalizers incrementally during mutation (f7bbc34)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/f7bbc343a624710ecf8f8f5eda620c4f35c90fc8/ghc

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commit f7bbc343a624710ecf8f8f5eda620c4f35c90fc8
Author: Simon Marlow <marlowsd at gmail.com>
Date:   Sun Mar 25 14:04:02 2018 -0400

    Run C finalizers incrementally during mutation
    
    With a large heap it's possible to build up a lot of finalizers
    between GCs.  We've observed GC spending up to 50% of its time running
    finalizers.  But there's no reason we have to run finalizers during
    GC, and especially no reason we have to block *all* the mutator
    threads while *one* GC thread runs finalizers one by one.
    
    I thought about a bunch of alternative ways to handle this, which are
    documented along with runSomeFinalizers() in Weak.c.  The approach I
    settled on is to have a capability run finalizers if it is idle.  So
    running finalizers is like a low-priority background thread. This
    requires some minor scheduler changes, but not much.  In the future we
    might be able to move more GC work into here (I have my eye on freeing
    large blocks, for example).
    
    Test Plan:
    * validate
    * tested on our system and saw reductions in GC pauses of 40-50%.
    
    Reviewers: bgamari, niteria, osa1, erikd
    
    Reviewed By: bgamari, osa1
    
    Subscribers: rwbarton, thomie, carter
    
    Differential Revision: https://phabricator.haskell.org/D4521


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f7bbc343a624710ecf8f8f5eda620c4f35c90fc8
 rts/Schedule.c |  14 ++++++-
 rts/Weak.c     | 119 +++++++++++++++++++++++++++++++++++++++++++++++++++------
 rts/Weak.h     |   1 +
 rts/sm/GC.c    |  25 ++++++++++++
 rts/sm/GC.h    |   2 +
 5 files changed, 149 insertions(+), 12 deletions(-)

Diff suppressed because of size. To see it, use:

    git diff-tree --root --patch-with-stat --no-color --find-copies-harder --ignore-space-at-eol --cc f7bbc343a624710ecf8f8f5eda620c4f35c90fc8