runtime/internal/atomic, sync: improve performance for atomics in ppc64x #21348

laboger · 2017-08-08T17:41:08Z

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (`go version`)?

upstream

What operating system and processor architecture are you using (`go env`)?

Ubuntu ppc64le

The current atomic function implementations for ppc64le within golang are all heavy weight, i.e., use hwsync since that is necessary if golang requires sequential consistency. For user code, if that is what the language requires, then we are stuck with it. However, there are several functions in the golang runtime with comments that say either "fast atomic", "load-acquire", or "store-release" and if the comments are still valid then more efficient atomic functions could be implemented which would allow these to perform better on ppc64le.

This topic was discussed in a meeting last year with @rsc and some of our memory model experts.

Essentially the idea would be:

implement atomic functions for load-acquire, store-release which would use light weight syncs instead of heavy weight syncs and possibly other improvements and use those functions where possible
try to understand what is actually meant by "fast atomic" in the comments of the runtime code and use lighter weight atomic functions for those cases where possible.

I put ppc64le in the title but it's possible this might help other platforms too.

The text was updated successfully, but these errors were encountered:

laboger · 2018-02-20T20:18:11Z

Changed the title to be more generic, since some general improvements will be made as well as adding some functions that could be used to do load-acquire or store-release.

gopherbot · 2018-03-01T20:58:11Z

Change https://golang.org/cl/95175 mentions this issue: cmd/compile/internal/ppc64, runtime internal/atomic, sync/atomic: implement faster atomics for ppc64x

…lement faster atomics for ppc64x This change implements faster atomics for ppc64x based on the ISA 2.07B, Appendix B.2 recommendations, replacing SYNC/ISYNC by LWSYNC in some cases. Updates #21348 name old time/op new time/op delta Cond1-16 955ns 856ns -10.33% Cond2-16 2.38µs 2.03µs -14.59% Cond4-16 5.90µs 5.44µs -7.88% Cond8-16 12.1µs 11.1µs -8.42% Cond16-16 27.0µs 25.1µs -7.04% Cond32-16 59.1µs 55.5µs -6.14% LoadMostlyHits/*sync_test.DeepCopyMap-16 22.1ns 24.1ns +9.02% LoadMostlyHits/*sync_test.RWMutexMap-16 252ns 249ns -1.20% LoadMostlyHits/*sync.Map-16 16.2ns 16.3ns ~ LoadMostlyMisses/*sync_test.DeepCopyMap-16 22.3ns 22.6ns ~ LoadMostlyMisses/*sync_test.RWMutexMap-16 249ns 247ns -0.51% LoadMostlyMisses/*sync.Map-16 12.7ns 12.7ns ~ LoadOrStoreBalanced/*sync_test.RWMutexMap-16 1.27µs 1.17µs -7.54% LoadOrStoreBalanced/*sync.Map-16 1.12µs 1.10µs -2.35% LoadOrStoreUnique/*sync_test.RWMutexMap-16 1.75µs 1.68µs -3.84% LoadOrStoreUnique/*sync.Map-16 2.07µs 1.97µs -5.13% LoadOrStoreCollision/*sync_test.DeepCopyMap-16 15.8ns 15.9ns ~ LoadOrStoreCollision/*sync_test.RWMutexMap-16 496ns 424ns -14.48% LoadOrStoreCollision/*sync.Map-16 6.07ns 6.07ns ~ Range/*sync_test.DeepCopyMap-16 1.65µs 1.64µs ~ Range/*sync_test.RWMutexMap-16 278µs 288µs +3.75% Range/*sync.Map-16 2.00µs 2.01µs ~ AdversarialAlloc/*sync_test.DeepCopyMap-16 3.45µs 3.44µs ~ AdversarialAlloc/*sync_test.RWMutexMap-16 226ns 227ns ~ AdversarialAlloc/*sync.Map-16 1.09µs 1.07µs -2.36% AdversarialDelete/*sync_test.DeepCopyMap-16 553ns 550ns -0.57% AdversarialDelete/*sync_test.RWMutexMap-16 273ns 274ns ~ AdversarialDelete/*sync.Map-16 247ns 249ns ~ UncontendedSemaphore-16 79.0ns 65.5ns -17.11% ContendedSemaphore-16 112ns 97ns -13.77% MutexUncontended-16 3.34ns 2.51ns -24.69% Mutex-16 266ns 191ns -28.26% MutexSlack-16 226ns 159ns -29.55% MutexWork-16 377ns 338ns -10.14% MutexWorkSlack-16 335ns 308ns -8.20% MutexNoSpin-16 196ns 184ns -5.91% MutexSpin-16 710ns 666ns -6.21% Once-16 1.29ns 1.29ns ~ Pool-16 8.64ns 8.71ns ~ PoolOverflow-16 1.60µs 1.44µs -10.25% SemaUncontended-16 5.39ns 4.42ns -17.96% SemaSyntNonblock-16 539ns 483ns -10.42% SemaSyntBlock-16 413ns 354ns -14.20% SemaWorkNonblock-16 305ns 258ns -15.36% SemaWorkBlock-16 266ns 229ns -14.06% RWMutexUncontended-16 12.9ns 9.7ns -24.80% RWMutexWrite100-16 203ns 147ns -27.47% RWMutexWrite10-16 177ns 119ns -32.74% RWMutexWorkWrite100-16 435ns 403ns -7.39% RWMutexWorkWrite10-16 642ns 611ns -4.79% WaitGroupUncontended-16 4.67ns 3.70ns -20.92% WaitGroupAddDone-16 402ns 355ns -11.54% WaitGroupAddDoneWork-16 208ns 250ns +20.09% WaitGroupWait-16 1.21ns 1.21ns ~ WaitGroupWaitWork-16 5.91ns 5.87ns -0.81% WaitGroupActuallyWait-16 92.2ns 85.8ns -6.91% Updates #21348 Change-Id: Ibb9b271d11b308264103829e176c6d9fe8f867d3 Reviewed-on: https://go-review.googlesource.com/95175 Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>

…lement faster atomics for ppc64x This change implements faster atomics for ppc64x based on the ISA 2.07B, Appendix B.2 recommendations, replacing SYNC/ISYNC by LWSYNC in some cases. Updates golang#21348 name old time/op new time/op delta Cond1-16 955ns 856ns -10.33% Cond2-16 2.38µs 2.03µs -14.59% Cond4-16 5.90µs 5.44µs -7.88% Cond8-16 12.1µs 11.1µs -8.42% Cond16-16 27.0µs 25.1µs -7.04% Cond32-16 59.1µs 55.5µs -6.14% LoadMostlyHits/*sync_test.DeepCopyMap-16 22.1ns 24.1ns +9.02% LoadMostlyHits/*sync_test.RWMutexMap-16 252ns 249ns -1.20% LoadMostlyHits/*sync.Map-16 16.2ns 16.3ns ~ LoadMostlyMisses/*sync_test.DeepCopyMap-16 22.3ns 22.6ns ~ LoadMostlyMisses/*sync_test.RWMutexMap-16 249ns 247ns -0.51% LoadMostlyMisses/*sync.Map-16 12.7ns 12.7ns ~ LoadOrStoreBalanced/*sync_test.RWMutexMap-16 1.27µs 1.17µs -7.54% LoadOrStoreBalanced/*sync.Map-16 1.12µs 1.10µs -2.35% LoadOrStoreUnique/*sync_test.RWMutexMap-16 1.75µs 1.68µs -3.84% LoadOrStoreUnique/*sync.Map-16 2.07µs 1.97µs -5.13% LoadOrStoreCollision/*sync_test.DeepCopyMap-16 15.8ns 15.9ns ~ LoadOrStoreCollision/*sync_test.RWMutexMap-16 496ns 424ns -14.48% LoadOrStoreCollision/*sync.Map-16 6.07ns 6.07ns ~ Range/*sync_test.DeepCopyMap-16 1.65µs 1.64µs ~ Range/*sync_test.RWMutexMap-16 278µs 288µs +3.75% Range/*sync.Map-16 2.00µs 2.01µs ~ AdversarialAlloc/*sync_test.DeepCopyMap-16 3.45µs 3.44µs ~ AdversarialAlloc/*sync_test.RWMutexMap-16 226ns 227ns ~ AdversarialAlloc/*sync.Map-16 1.09µs 1.07µs -2.36% AdversarialDelete/*sync_test.DeepCopyMap-16 553ns 550ns -0.57% AdversarialDelete/*sync_test.RWMutexMap-16 273ns 274ns ~ AdversarialDelete/*sync.Map-16 247ns 249ns ~ UncontendedSemaphore-16 79.0ns 65.5ns -17.11% ContendedSemaphore-16 112ns 97ns -13.77% MutexUncontended-16 3.34ns 2.51ns -24.69% Mutex-16 266ns 191ns -28.26% MutexSlack-16 226ns 159ns -29.55% MutexWork-16 377ns 338ns -10.14% MutexWorkSlack-16 335ns 308ns -8.20% MutexNoSpin-16 196ns 184ns -5.91% MutexSpin-16 710ns 666ns -6.21% Once-16 1.29ns 1.29ns ~ Pool-16 8.64ns 8.71ns ~ PoolOverflow-16 1.60µs 1.44µs -10.25% SemaUncontended-16 5.39ns 4.42ns -17.96% SemaSyntNonblock-16 539ns 483ns -10.42% SemaSyntBlock-16 413ns 354ns -14.20% SemaWorkNonblock-16 305ns 258ns -15.36% SemaWorkBlock-16 266ns 229ns -14.06% RWMutexUncontended-16 12.9ns 9.7ns -24.80% RWMutexWrite100-16 203ns 147ns -27.47% RWMutexWrite10-16 177ns 119ns -32.74% RWMutexWorkWrite100-16 435ns 403ns -7.39% RWMutexWorkWrite10-16 642ns 611ns -4.79% WaitGroupUncontended-16 4.67ns 3.70ns -20.92% WaitGroupAddDone-16 402ns 355ns -11.54% WaitGroupAddDoneWork-16 208ns 250ns +20.09% WaitGroupWait-16 1.21ns 1.21ns ~ WaitGroupWaitWork-16 5.91ns 5.87ns -0.81% WaitGroupActuallyWait-16 92.2ns 85.8ns -6.91% Updates golang#21348 Change-Id: Ibb9b271d11b308264103829e176c6d9fe8f867d3 Reviewed-on: https://go-review.googlesource.com/95175 Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>

gopherbot · 2018-10-23T18:01:19Z

Change https://golang.org/cl/142277 mentions this issue: cmd/compile, runtime: add new lightweight atomics for ppc64x

laboger changed the title ~~runtime/internal/atomic, sync: implement lighter weight atomic functions for runtime internal use where possible on ppc64le~~ runtime/internal/atomic, sync: improve performance for atomics in ppc64x Feb 20, 2018

andybons added the NeedsFix The path to resolution is known, but the work has not been done. label Mar 13, 2018

andybons added this to the Unplanned milestone Mar 13, 2018

gopherbot closed this as completed in 5c47213 Oct 23, 2018

golang locked and limited conversation to collaborators Oct 23, 2019

gopherbot added the FrozenDueToAge label Oct 23, 2019

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runtime/internal/atomic, sync: improve performance for atomics in ppc64x #21348

runtime/internal/atomic, sync: improve performance for atomics in ppc64x #21348

laboger commented Aug 8, 2017

laboger commented Feb 20, 2018

gopherbot commented Mar 1, 2018

gopherbot commented Oct 23, 2018

runtime/internal/atomic, sync: improve performance for atomics in ppc64x #21348

runtime/internal/atomic, sync: improve performance for atomics in ppc64x #21348

Comments

laboger commented Aug 8, 2017

What version of Go are you using (go version)?

What operating system and processor architecture are you using (go env)?

laboger commented Feb 20, 2018

gopherbot commented Mar 1, 2018

gopherbot commented Oct 23, 2018

What version of Go are you using (`go version`)?

What operating system and processor architecture are you using (`go env`)?