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runtime: skip atomics in heapBitsSetType when GC is not running
Suggested by Rick during code review of this code, but separated out for easier diagnosis in case it causes problems (and also easier rollback). name old mean new mean delta SetTypePtr 13.9ns × (0.98,1.05) 6.2ns × (0.99,1.01) -55.18% (p=0.000) SetTypePtr8 15.5ns × (0.95,1.10) 15.5ns × (0.99,1.05) ~ (p=0.952) SetTypePtr16 17.8ns × (0.99,1.05) 18.0ns × (1.00,1.00) ~ (p=0.157) SetTypePtr32 25.2ns × (0.99,1.01) 24.3ns × (0.99,1.01) -3.86% (p=0.000) SetTypePtr64 42.2ns × (0.93,1.13) 40.8ns × (0.99,1.01) ~ (p=0.239) SetTypePtr126 67.3ns × (1.00,1.00) 67.5ns × (0.99,1.02) ~ (p=0.365) SetTypePtr128 67.6ns × (1.00,1.01) 70.1ns × (0.97,1.10) ~ (p=0.063) SetTypePtrSlice 575ns × (0.98,1.06) 543ns × (0.95,1.17) -5.54% (p=0.034) SetTypeNode1 12.4ns × (0.98,1.09) 12.8ns × (0.99,1.01) +3.40% (p=0.021) SetTypeNode1Slice 97.1ns × (0.97,1.09) 89.5ns × (1.00,1.00) -7.78% (p=0.000) SetTypeNode8 29.8ns × (1.00,1.01) 17.7ns × (1.00,1.01) -40.74% (p=0.000) SetTypeNode8Slice 204ns × (0.99,1.04) 190ns × (0.97,1.06) -6.96% (p=0.000) SetTypeNode64 42.8ns × (0.99,1.01) 44.0ns × (0.95,1.12) ~ (p=0.163) SetTypeNode64Slice 1.00µs × (0.95,1.09) 0.98µs × (0.96,1.08) ~ (p=0.356) SetTypeNode64Dead 12.2ns × (0.99,1.04) 12.7ns × (1.00,1.01) +4.34% (p=0.000) SetTypeNode64DeadSlice 1.14µs × (0.94,1.11) 0.99µs × (0.99,1.03) -13.74% (p=0.000) SetTypeNode124 67.9ns × (0.99,1.03) 70.4ns × (0.95,1.15) ~ (p=0.115) SetTypeNode124Slice 1.76µs × (0.99,1.04) 1.88µs × (0.91,1.23) ~ (p=0.096) SetTypeNode126 67.7ns × (1.00,1.01) 68.2ns × (0.99,1.02) +0.72% (p=0.014) SetTypeNode126Slice 1.76µs × (1.00,1.01) 1.87µs × (0.93,1.15) +6.15% (p=0.035) SetTypeNode1024 462ns × (0.96,1.10) 451ns × (0.99,1.05) ~ (p=0.224) SetTypeNode1024Slice 14.4µs × (0.95,1.15) 14.2µs × (0.97,1.19) ~ (p=0.676) name old mean new mean delta BinaryTree17 5.87s × (0.98,1.04) 5.87s × (0.98,1.03) ~ (p=0.993) Fannkuch11 4.39s × (0.99,1.01) 4.34s × (1.00,1.01) -1.22% (p=0.000) FmtFprintfEmpty 90.6ns × (0.97,1.06) 89.4ns × (0.97,1.03) ~ (p=0.070) FmtFprintfString 305ns × (0.98,1.02) 296ns × (0.99,1.02) -2.94% (p=0.000) FmtFprintfInt 276ns × (0.97,1.04) 270ns × (0.98,1.03) -2.17% (p=0.001) FmtFprintfIntInt 490ns × (0.97,1.05) 473ns × (0.99,1.02) -3.59% (p=0.000) FmtFprintfPrefixedInt 402ns × (0.99,1.02) 397ns × (0.99,1.01) -1.15% (p=0.000) FmtFprintfFloat 577ns × (0.99,1.01) 549ns × (0.99,1.01) -4.78% (p=0.000) FmtManyArgs 1.89µs × (0.99,1.02) 1.87µs × (0.99,1.01) -1.43% (p=0.000) GobDecode 15.2ms × (0.99,1.01) 14.7ms × (0.99,1.02) -3.55% (p=0.000) GobEncode 11.7ms × (0.98,1.04) 11.5ms × (0.99,1.02) -1.63% (p=0.002) Gzip 647ms × (0.99,1.01) 647ms × (1.00,1.01) ~ (p=0.486) Gunzip 142ms × (1.00,1.00) 143ms × (1.00,1.00) ~ (p=0.234) HTTPClientServer 90.7µs × (0.99,1.01) 90.4µs × (0.98,1.04) ~ (p=0.331) JSONEncode 31.9ms × (0.97,1.06) 31.6ms × (0.98,1.02) ~ (p=0.206) JSONDecode 110ms × (0.99,1.01) 112ms × (0.99,1.02) +1.48% (p=0.000) Mandelbrot200 6.00ms × (1.00,1.00) 6.01ms × (1.00,1.00) ~ (p=0.058) GoParse 6.63ms × (0.98,1.03) 6.61ms × (0.98,1.02) ~ (p=0.353) RegexpMatchEasy0_32 162ns × (0.99,1.01) 161ns × (1.00,1.00) -0.33% (p=0.004) RegexpMatchEasy0_1K 539ns × (0.99,1.01) 540ns × (0.99,1.02) ~ (p=0.222) RegexpMatchEasy1_32 139ns × (0.99,1.01) 140ns × (0.97,1.03) ~ (p=0.054) RegexpMatchEasy1_1K 886ns × (1.00,1.00) 887ns × (1.00,1.00) +0.18% (p=0.001) RegexpMatchMedium_32 252ns × (1.00,1.01) 252ns × (1.00,1.00) +0.21% (p=0.010) RegexpMatchMedium_1K 72.7µs × (1.00,1.01) 72.6µs × (1.00,1.00) ~ (p=0.060) RegexpMatchHard_32 3.84µs × (1.00,1.00) 3.84µs × (1.00,1.00) ~ (p=0.065) RegexpMatchHard_1K 117µs × (1.00,1.00) 117µs × (1.00,1.00) -0.27% (p=0.000) Revcomp 916ms × (0.98,1.04) 909ms × (0.99,1.01) ~ (p=0.054) Template 126ms × (0.99,1.01) 128ms × (0.99,1.02) +1.43% (p=0.000) TimeParse 632ns × (0.99,1.01) 625ns × (1.00,1.01) -1.05% (p=0.000) TimeFormat 655ns × (0.99,1.02) 669ns × (0.99,1.02) +2.01% (p=0.000) Change-Id: I9477b7c9489c6fa98e860c190ce06cd73c53c6a1 Reviewed-on: https://go-review.googlesource.com/9829 Reviewed-by: Rick Hudson <rlh@golang.org> Reviewed-by: Austin Clements <austin@google.com>
This commit is contained in:
Russ Cox
parent
b83b011100
commit
5b3739357a
@ -549,11 +549,19 @@ func heapBitsSetType(x, size, dataSize uintptr, typ *_type) {
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// The bitmap byte is shared with the one-word object
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// next to it, and concurrent GC might be marking that
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// object, so we must use an atomic update.
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// We can skip this if the GC is completely off.
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// Note that there is some marking that happens during
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// gcphase == _GCscan, for completely scalar objects,
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// so it is not safe to check just for the marking phases.
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// TODO(rsc): It may make sense to set all the pointer bits
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// when initializing the span, and then the atomicor8 here
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// goes away - heapBitsSetType would be a no-op
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// in that case.
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atomicor8(h.bitp, bitPointer<<h.shift)
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if gcphase == _GCoff {
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*h.bitp |= bitPointer << h.shift
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} else {
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atomicor8(h.bitp, bitPointer<<h.shift)
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}
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return
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}
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@ -593,13 +601,21 @@ func heapBitsSetType(x, size, dataSize uintptr, typ *_type) {
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if size == 2*ptrSize {
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if typ.size == ptrSize {
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// 2-element slice of pointer.
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atomicor8(h.bitp, (bitPointer|bitPointer<<heapBitsShift)<<h.shift)
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if gcphase == _GCoff {
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*h.bitp |= (bitPointer | bitPointer<<heapBitsShift) << h.shift
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} else {
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atomicor8(h.bitp, (bitPointer|bitPointer<<heapBitsShift)<<h.shift)
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}
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return
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}
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// Otherwise typ.size must be 2*ptrSize, and typ.kind&kindGCProg == 0.
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b := uint32(*ptrmask)
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hb := b & 3
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atomicor8(h.bitp, uint8(hb<<h.shift))
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if gcphase == _GCoff {
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*h.bitp |= uint8(hb << h.shift)
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} else {
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atomicor8(h.bitp, uint8(hb<<h.shift))
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}
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return
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}
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@ -779,7 +795,11 @@ func heapBitsSetType(x, size, dataSize uintptr, typ *_type) {
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b >>= 2
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nb -= 2
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// Note: no bitMarker in hb because the first two words don't get markers from us.
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atomicor8(hbitp, uint8(hb))
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if gcphase == _GCoff {
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*hbitp |= uint8(hb)
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} else {
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atomicor8(hbitp, uint8(hb))
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}
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hbitp = subtractb(hbitp, 1)
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if w += 2; w >= nw {
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// We know that there is more data, because we handled 2-word objects above.
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