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| author | Russ Cox <rsc@golang.org> | 2017-02-03 19:26:13 -0500 |
|---|---|---|
| committer | Russ Cox <rsc@golang.org> | 2017-02-09 14:45:16 +0000 |
| commit | e4371fb179ad69cbd057f2430120843948e09f2f (patch) | |
| tree | 4e49771324f1f6bd35b2b962a9511fb9bb071455 /src/runtime/mstats.go | |
| parent | 3a6842a0ecf66cf06ce4f0a5fcb9c09fbfdbecc1 (diff) | |
| download | go-e4371fb179ad69cbd057f2430120843948e09f2f.tar.gz go-e4371fb179ad69cbd057f2430120843948e09f2f.zip | |
time: optimize Now on darwin, windows
Fetch both monotonic and wall time together when possible.
Avoids skew and is cheaper.
Also shave a few ns off in conversion in package time.
Compared to current implementation (after monotonic changes):
name old time/op new time/op delta
Now 19.6ns ± 1% 9.7ns ± 1% -50.63% (p=0.000 n=41+49) darwin/amd64
Now 23.5ns ± 4% 10.6ns ± 5% -54.61% (p=0.000 n=30+28) windows/amd64
Now 54.5ns ± 5% 29.8ns ± 9% -45.40% (p=0.000 n=27+29) windows/386
More importantly, compared to Go 1.8:
name old time/op new time/op delta
Now 9.5ns ± 1% 9.7ns ± 1% +1.94% (p=0.000 n=41+49) darwin/amd64
Now 12.9ns ± 5% 10.6ns ± 5% -17.73% (p=0.000 n=30+28) windows/amd64
Now 15.3ns ± 5% 29.8ns ± 9% +94.36% (p=0.000 n=30+29) windows/386
This brings time.Now back in line with Go 1.8 on darwin/amd64 and windows/amd64.
It's not obvious why windows/386 is still noticeably worse than Go 1.8,
but it's better than before this CL. The windows/386 speed is not too
important; the changes just keep the two architectures similar.
Change-Id: If69b94970c8a1a57910a371ee91e0d4e82e46c5d
Reviewed-on: https://go-review.googlesource.com/36428
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Diffstat (limited to 'src/runtime/mstats.go')
| -rw-r--r-- | src/runtime/mstats.go | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/src/runtime/mstats.go b/src/runtime/mstats.go index 41b9005731..8fb34f724f 100644 --- a/src/runtime/mstats.go +++ b/src/runtime/mstats.go @@ -72,7 +72,7 @@ type mstats struct { // Statistics about garbage collector. // Protected by mheap or stopping the world during GC. next_gc uint64 // goal heap_live for when next GC ends; ^0 if disabled - last_gc uint64 // last gc (in absolute time) + last_gc_unix uint64 // last gc (in unix time) pause_total_ns uint64 pause_ns [256]uint64 // circular buffer of recent gc pause lengths pause_end [256]uint64 // circular buffer of recent gc end times (nanoseconds since 1970) @@ -92,7 +92,8 @@ type mstats struct { // Statistics below here are not exported to MemStats directly. - tinyallocs uint64 // number of tiny allocations that didn't cause actual allocation; not exported to go directly + last_gc_nanotime uint64 // last gc (monotonic time) + tinyallocs uint64 // number of tiny allocations that didn't cause actual allocation; not exported to go directly // gc_trigger is the heap size that triggers marking. // @@ -497,7 +498,7 @@ func readGCStats_m(pauses *[]uint64) { p[n+i] = memstats.pause_end[j] } - p[n+n] = memstats.last_gc + p[n+n] = memstats.last_gc_unix p[n+n+1] = uint64(memstats.numgc) p[n+n+2] = memstats.pause_total_ns unlock(&mheap_.lock) |