| commit | 18705721807abd31888609920cce6a2b59e67ab7 | [log] [tgz] |
|---|---|---|
| author | Austin Clements <austin@google.com> | Fri Oct 02 09:51:12 2015 -0400 |
| committer | Austin Clements <austin@google.com> | Tue Nov 03 15:53:38 2015 +0000 |
| tree | a4672d8409865ff2680186b0ef913b417dd8bd7b | |
| parent | 456528304d4a20ee438b440fd6807c3f5ca7d5e2 [diff] |
runtime: enlarge GC work buffer size Currently the GC work buffers are only 256 bytes and hence can record only 24 64-bit pointer. They were reduced from 4K in commits db7fd1c and a15818f as a way to minimize the amount of work the per-P workbuf caches could "hide" from the mark phase and carry in to the mark termination phase. However, this approach wasn't very robust and we later added a "mark 2" phase to address this problem head-on. Because of mark 2, there's now no benefit to having very small work buffers. But there are plenty of downsides: small work buffers increase contention on the work lists, increase the frequency and hence net overhead of acquiring and releasing work buffers, and somewhat increase memory overhead of the GC. This commit expands work buffers back to 4K (504 64-bit pointers). This reduces the rate of writes to work.full in the garbage benchmark from a peak of ~780,000 writes/sec to a peak of ~32,000 writes/sec. This has negligible effect on the go1 benchmarks. It slightly slows down the garbage benchmark. name old time/op new time/op delta XBenchGarbage-12 5.37ms ± 5% 5.60ms ± 2% +4.37% (p=0.000 n=20+20) Change-Id: Ic9cc28e7a125d23d9faf4f5e690fb8aa9bcdfb28 Reviewed-on: https://go-review.googlesource.com/15893 Reviewed-by: Rick Hudson <rlh@golang.org> Run-TryBot: Austin Clements <austin@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
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