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runtime: add pcvalue cache to improve stack scan speed
The cost of scanning large stacks is currently dominated by the time spent looking up and decoding the pcvalue table. However, large stacks are usually large not because they contain calls to many different functions, but because they contain many calls to the same, small set of recursive functions. Hence, walking large stacks tends to make the same pcvalue queries many times. Based on this observation, this commit adds a small, very simple, and fast cache in front of pcvalue lookup. We thread this cache down from operations that make many pcvalue calls, such as gentraceback, stack scanning, and stack adjusting. This simple cache works well because it has minimal overhead when it's not effective. I also tried a hashed direct-map cache, CLOCK-based replacement, round-robin replacement, and round-robin with lookups disabled until there had been at least 16 probes, but none of these approaches had obvious wins over the random replacement policy in this commit. This nearly doubles the overall performance of the deep stack test program from issue #10898: name old time/op new time/op delta Issue10898 16.5s ±12% 9.2s ±12% -44.37% (p=0.008 n=5+5) It's a very slight win on the garbage benchmark: name old time/op new time/op delta XBenchGarbage-12 4.92ms ± 1% 4.89ms ± 1% -0.75% (p=0.000 n=18+19) It's a wash (but doesn't harm performance) on the go1 benchmarks, which don't have particularly deep stacks: name old time/op new time/op delta BinaryTree17-12 3.11s ± 2% 3.20s ± 3% +2.83% (p=0.000 n=17+20) Fannkuch11-12 2.51s ± 1% 2.51s ± 1% -0.22% (p=0.034 n=19+18) FmtFprintfEmpty-12 50.8ns ± 3% 50.6ns ± 2% ~ (p=0.793 n=20+20) FmtFprintfString-12 174ns ± 0% 174ns ± 1% +0.17% (p=0.048 n=15+20) FmtFprintfInt-12 177ns ± 0% 165ns ± 1% -6.99% (p=0.000 n=17+19) FmtFprintfIntInt-12 283ns ± 1% 284ns ± 0% +0.22% (p=0.000 n=18+15) FmtFprintfPrefixedInt-12 243ns ± 1% 244ns ± 1% +0.40% (p=0.000 n=20+19) FmtFprintfFloat-12 318ns ± 0% 319ns ± 0% +0.27% (p=0.001 n=19+20) FmtManyArgs-12 1.12µs ± 0% 1.14µs ± 0% +1.74% (p=0.000 n=19+20) GobDecode-12 8.69ms ± 0% 8.73ms ± 1% +0.46% (p=0.000 n=18+18) GobEncode-12 6.64ms ± 1% 6.61ms ± 1% -0.46% (p=0.000 n=20+20) Gzip-12 323ms ± 2% 319ms ± 1% -1.11% (p=0.000 n=20+20) Gunzip-12 42.8ms ± 0% 42.9ms ± 0% ~ (p=0.158 n=18+20) HTTPClientServer-12 63.3µs ± 1% 63.1µs ± 1% -0.35% (p=0.011 n=20+20) JSONEncode-12 16.9ms ± 1% 17.3ms ± 1% +2.84% (p=0.000 n=19+20) JSONDecode-12 59.7ms ± 0% 58.5ms ± 0% -2.05% (p=0.000 n=19+17) Mandelbrot200-12 3.92ms ± 0% 3.91ms ± 0% -0.16% (p=0.003 n=19+19) GoParse-12 3.79ms ± 2% 3.75ms ± 2% -0.91% (p=0.005 n=20+20) RegexpMatchEasy0_32-12 102ns ± 1% 101ns ± 1% -0.80% (p=0.001 n=14+20) RegexpMatchEasy0_1K-12 337ns ± 1% 346ns ± 1% +2.90% (p=0.000 n=20+19) RegexpMatchEasy1_32-12 84.4ns ± 2% 84.3ns ± 2% ~ (p=0.743 n=20+20) RegexpMatchEasy1_1K-12 502ns ± 1% 505ns ± 0% +0.64% (p=0.000 n=20+20) RegexpMatchMedium_32-12 133ns ± 1% 132ns ± 1% -0.85% (p=0.000 n=20+19) RegexpMatchMedium_1K-12 40.1µs ± 1% 39.8µs ± 1% -0.77% (p=0.000 n=18+18) RegexpMatchHard_32-12 2.08µs ± 1% 2.07µs ± 1% -0.55% (p=0.001 n=18+19) RegexpMatchHard_1K-12 62.4µs ± 1% 62.0µs ± 1% -0.74% (p=0.000 n=19+19) Revcomp-12 545ms ± 2% 545ms ± 3% ~ (p=0.771 n=19+20) Template-12 73.7ms ± 1% 72.0ms ± 0% -2.33% (p=0.000 n=20+18) TimeParse-12 358ns ± 1% 351ns ± 1% -2.07% (p=0.000 n=20+20) TimeFormat-12 369ns ± 1% 356ns ± 0% -3.53% (p=0.000 n=20+18) [Geo mean] 63.5µs 63.2µs -0.41% name old speed new speed delta GobDecode-12 88.3MB/s ± 0% 87.9MB/s ± 0% -0.43% (p=0.000 n=18+17) GobEncode-12 116MB/s ± 1% 116MB/s ± 1% +0.47% (p=0.000 n=20+20) Gzip-12 60.2MB/s ± 2% 60.8MB/s ± 1% +1.13% (p=0.000 n=20+20) Gunzip-12 453MB/s ± 0% 453MB/s ± 0% ~ (p=0.160 n=18+20) JSONEncode-12 115MB/s ± 1% 112MB/s ± 1% -2.76% (p=0.000 n=19+20) JSONDecode-12 32.5MB/s ± 0% 33.2MB/s ± 0% +2.09% (p=0.000 n=19+17) GoParse-12 15.3MB/s ± 2% 15.4MB/s ± 2% +0.92% (p=0.004 n=20+20) RegexpMatchEasy0_32-12 311MB/s ± 1% 314MB/s ± 1% +0.78% (p=0.000 n=15+19) RegexpMatchEasy0_1K-12 3.04GB/s ± 1% 2.95GB/s ± 1% -2.90% (p=0.000 n=19+19) RegexpMatchEasy1_32-12 379MB/s ± 2% 380MB/s ± 2% ~ (p=0.779 n=20+20) RegexpMatchEasy1_1K-12 2.04GB/s ± 1% 2.02GB/s ± 0% -0.62% (p=0.000 n=20+20) RegexpMatchMedium_32-12 7.46MB/s ± 1% 7.53MB/s ± 1% +0.86% (p=0.000 n=20+19) RegexpMatchMedium_1K-12 25.5MB/s ± 1% 25.7MB/s ± 1% +0.78% (p=0.000 n=18+18) RegexpMatchHard_32-12 15.4MB/s ± 1% 15.5MB/s ± 1% +0.62% (p=0.000 n=19+19) RegexpMatchHard_1K-12 16.4MB/s ± 1% 16.5MB/s ± 1% +0.82% (p=0.000 n=20+19) Revcomp-12 466MB/s ± 2% 466MB/s ± 3% ~ (p=0.765 n=19+20) Template-12 26.3MB/s ± 1% 27.0MB/s ± 0% +2.38% (p=0.000 n=20+18) [Geo mean] 97.8MB/s 98.0MB/s +0.23% Change-Id: I281044ae0b24990ba46487cacbc1069493274bc4 Reviewed-on: https://go-review.googlesource.com/13614 Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Austin Clements
parent
46630ecd65
commit
beedb1ec33
6 changed files with 68 additions and 18 deletions
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@ -482,6 +482,7 @@ var ptrnames = []string{
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type adjustinfo struct {
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old stack
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delta uintptr // ptr distance from old to new stack (newbase - oldbase)
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cache pcvalueCache
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}
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// Adjustpointer checks whether *vpp is in the old stack described by adjinfo.
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@ -575,7 +576,7 @@ func adjustframe(frame *stkframe, arg unsafe.Pointer) bool {
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if targetpc != f.entry {
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targetpc--
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}
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pcdata := pcdatavalue(f, _PCDATA_StackMapIndex, targetpc)
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pcdata := pcdatavalue(f, _PCDATA_StackMapIndex, targetpc, &adjinfo.cache)
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if pcdata == -1 {
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pcdata = 0 // in prologue
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}
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