| commit | 170fb100891fff56529b6816ab581af19a717fa9 | [log] [tgz] |
|---|---|---|
| author | Austin Clements <austin@google.com> | Fri Apr 17 16:26:55 2015 -0400 |
| committer | Austin Clements <austin@google.com> | Tue Apr 21 15:35:55 2015 +0000 |
| tree | 702ec6a2888bf245e86ee59da9dcdfbd0766cfd8 | |
| parent | e0c3d85f08431540abaaa909fb8185dfe05304b0 [diff] |
runtime: assist harder if GC exceeds the estimated marked heap Currently, the GC controller computes the mutator assist ratio at the beginning of the cycle by estimating that the marked heap size this cycle will be the same as it was the previous cycle. It then uses that assist ratio for the rest of the cycle. However, this means that if the mutator is quickly growing its reachable heap, the heap size is likely to exceed the heap goal and currently there's no additional pressure on mutator assists when this happens. For example, 6g (with GOMAXPROCS=1) frequently exceeds the goal heap size by ~25% because of this. This change makes GC revise its work estimate and the resulting assist ratio every 10ms during the concurrent mark. Instead of unconditionally using the marked heap size from the last cycle as an estimate for this cycle, it takes the minimum of the previously marked heap and the currently marked heap. As a result, as the cycle approaches or exceeds its heap goal, this will increase the assist ratio to put more pressure on the mutator assist to bring the cycle to an end. For 6g, this causes the GC to always finish within 5% and often within 1% of its heap goal. Change-Id: I4333b92ad0878c704964be42c655c38a862b4224 Reviewed-on: https://go-review.googlesource.com/9070 Reviewed-by: Rick Hudson <rlh@golang.org> Run-TryBot: Austin Clements <austin@google.com>
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