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author | Sergei Trofimovich <slyfox@gentoo.org> | 2016-09-02 10:26:43 +0100 |
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committer | Sergei Trofimovich <slyfox@gentoo.org> | 2016-09-02 10:29:51 +0100 |
commit | b3b64a95b9653963a2868278fd0130858a9eb9f0 (patch) | |
tree | 7228fae8f1f598deff28975b5f5a041ef879bc13 /metadata/md5-cache/dev-haskell/threads-0.5.1.4 | |
parent | media-video/vlc: add patches to build with ffmpeg3, bug #574788 (diff) | |
download | gentoo-b3b64a95b9653963a2868278fd0130858a9eb9f0.tar.gz gentoo-b3b64a95b9653963a2868278fd0130858a9eb9f0.tar.bz2 gentoo-b3b64a95b9653963a2868278fd0130858a9eb9f0.zip |
haskell-cabal.eclass: unleash full parallelism of parallel ghc
I've explored scalability of 'ghc --make -j' a bit in
https://ghc.haskell.org/trac/ghc/ticket/9221
Some takeaways:
- never specify -j<N> with N > CPU. garbage collector threads
waste kernel time running sched_yield()
- GHC allocates A Lot: large nursery decreases GC interruptions.
We fix it with '-A256M'
- for large nursery enabling work-stealing makes GC finish faster
on each collection cycle.
We fix it with -qb0
While at it move HCFLAGS setup after parallel defaults.
That allows user to override defaults with own HCFLAGS.
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
Diffstat (limited to 'metadata/md5-cache/dev-haskell/threads-0.5.1.4')
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