d6ef98b8fa
Currently bulkBarrierPreWrite follows a fairly slow path wherein it calls typePointersOf, which ends up calling into fastForward. This does some fairly heavy computation to move the iterator forward without any assumptions about where it lands at all. It needs to be completely general to support splitting at arbitrary boundaries, for example for scanning oblets. This means that copying objects during the GC mark phase is fairly expensive, and is a regression from before allocheaders. However, in almost all cases bulkBarrierPreWrite and bulkBarrierPreWriteSrcOnly have perfect type information. We can do a lot better in these cases because we're starting on a type-size boundary, which is exactly what the iterator is built around. This change adds the typePointersOfType method which produces a typePointers iterator from a pointer and a type. This change significantly improves the performance of these bulk write barriers, eliminating some performance regressions that were noticed on the perf dashboard. There are still just a couple cases where we have to use the more general typePointersOf calls, but they're fairly rare; most bulk barriers have perfect type information. This change is tested by the GCInfo tests in the runtime and the GCBits tests in the reflect package via an additional check in getgcmask. Results for tile38 before and after allocheaders. There was previous a regression in the p90, now it's gone. Also, the overall win has been boosted slightly. tile38 $ benchstat noallocheaders.results allocheaders.results name old time/op new time/op delta Tile38QueryLoad 481µs ± 1% 468µs ± 1% -2.71% (p=0.000 n=10+10) name old average-RSS-bytes new average-RSS-bytes delta Tile38QueryLoad 6.32GB ± 1% 6.23GB ± 0% -1.38% (p=0.000 n=9+8) name old peak-RSS-bytes new peak-RSS-bytes delta Tile38QueryLoad 6.49GB ± 1% 6.40GB ± 1% -1.38% (p=0.002 n=10+10) name old peak-VM-bytes new peak-VM-bytes delta Tile38QueryLoad 7.72GB ± 1% 7.64GB ± 1% -1.07% (p=0.007 n=10+10) name old p50-latency-ns new p50-latency-ns delta Tile38QueryLoad 212k ± 1% 205k ± 0% -3.02% (p=0.000 n=10+9) name old p90-latency-ns new p90-latency-ns delta Tile38QueryLoad 622k ± 1% 616k ± 1% -1.03% (p=0.005 n=10+10) name old p99-latency-ns new p99-latency-ns delta Tile38QueryLoad 4.55M ± 2% 4.39M ± 2% -3.51% (p=0.000 n=10+10) name old ops/s new ops/s delta Tile38QueryLoad 12.5k ± 1% 12.8k ± 1% +2.78% (p=0.000 n=10+10) Change-Id: I0a48f848eae8777d0fd6769c3a1fe449f8d9d0a6 Reviewed-on: https://go-review.googlesource.com/c/go/+/542219 Reviewed-by: Cherry Mui <cherryyz@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> |
||
|---|---|---|
| .github | ||
| api | ||
| doc | ||
| lib/time | ||
| misc | ||
| src | ||
| test | ||
| .gitattributes | ||
| .gitignore | ||
| codereview.cfg | ||
| CONTRIBUTING.md | ||
| go.env | ||
| LICENSE | ||
| PATENTS | ||
| README.md | ||
| SECURITY.md | ||
The Go Programming Language
Go is an open source programming language that makes it easy to build simple, reliable, and efficient software.
Gopher image by Renee French, licensed under Creative Commons 4.0 Attributions license.
Our canonical Git repository is located at https://go.googlesource.com/go. There is a mirror of the repository at https://github.com/golang/go.
Unless otherwise noted, the Go source files are distributed under the BSD-style license found in the LICENSE file.
Download and Install
Binary Distributions
Official binary distributions are available at https://go.dev/dl/.
After downloading a binary release, visit https://go.dev/doc/install for installation instructions.
Install From Source
If a binary distribution is not available for your combination of operating system and architecture, visit https://go.dev/doc/install/source for source installation instructions.
Contributing
Go is the work of thousands of contributors. We appreciate your help!
To contribute, please read the contribution guidelines at https://go.dev/doc/contribute.
Note that the Go project uses the issue tracker for bug reports and proposals only. See https://go.dev/wiki/Questions for a list of places to ask questions about the Go language.