| commit | 441502154fa5f78e93c9c7985fbea78a02c21f4f | [log] [tgz] |
|---|---|---|
| author | David Crawshaw <crawshaw@golang.org> | Thu Sep 29 20:21:52 2016 -0400 |
| committer | David Crawshaw <crawshaw@golang.org> | Fri Sep 30 13:31:07 2016 +0000 |
| tree | 9de383ed8173745ee95b63739796fc94f6fd5a2b | |
| parent | 9828b7c468029d54e90846e5e2fc23fd6d39782a [diff] |
runtime: remove defer from standard cgo call The endcgo function call is currently deferred in case a cgo callback into Go panics and unwinds through cgocall. Typical cgo calls do not have callbacks into Go, and even fewer panic, so we pay the cost of this defer for no typical benefit. Amazingly, there is another defer on the cgocallback path also used to cleanup in case the Go code called by cgo panics. This CL folds the first defer into the second, to reduce the cost of typical cgo calls. This reduces the overhead for a no-op cgo call significantly: name old time/op new time/op delta CgoNoop-8 93.5ns ± 0% 51.1ns ± 1% -45.34% (p=0.016 n=4+5) The total effect between Go 1.7 and 1.8 is even greater, as CL 29656 reduced the cost of defer recently. Hopefully a future Go release will drop the cost of defer to nothing, making this optimization unnecessary. But until then, this is nice. Change-Id: Id1a5648f687a87001d95bec6842e4054bd20ee4f Reviewed-on: https://go-review.googlesource.com/30080 Run-TryBot: David Crawshaw <crawshaw@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
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