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12 Commits

Author SHA1 Message Date
Jamie Liu 9bd0164237 Improve sync.SeqCount performance. 
- Make sync.SeqCountEpoch not a struct. This allows sync.SeqCount.BeginRead()
  to be inlined.

- Mark sync.SeqAtomicLoad<T> nosplit to mitigate the Go compiler's refusal to
  inline it. (Best I could get was "cost 92 exceeds budget 80".)

- Use runtime-guided spinning in SeqCount.BeginRead().

Benchmarks:
name                               old time/op  new time/op   delta
pkg:pkg/sync/sync goos:linux goarch:amd64
SeqCountWriteUncontended-12        8.24ns ± 0%  11.40ns ± 0%  +38.35%  (p=0.000 n=10+10)
SeqCountReadUncontended-12         0.33ns ± 0%   0.14ns ± 3%  -57.77%  (p=0.000 n=7+8)
pkg:pkg/sync/seqatomictest/seqatomic goos:linux goarch:amd64
SeqAtomicLoadIntUncontended-12     0.64ns ± 1%   0.41ns ± 1%  -36.40%  (p=0.000 n=10+8)
SeqAtomicTryLoadIntUncontended-12  0.18ns ± 4%   0.18ns ± 1%     ~     (p=0.206 n=10+8)
AtomicValueLoadIntUncontended-12   0.27ns ± 3%   0.27ns ± 0%   -1.77%  (p=0.000 n=10+8)

(atomic.Value.Load is, of course, inlined. We would expect an uncontended
inline SeqAtomicLoad<int> to perform identically to SeqAtomicTryLoad<int>.) The
"regression" in BenchmarkSeqCountWriteUncontended, despite this CL changing
nothing in that path, is attributed to microarchitectural subtlety; the
benchmark loop is unchanged except for its address:

Before this CL:
  :0                    0x4e62d1                48ffc2                  INCQ DX
  :0                    0x4e62d4                48399110010000          CMPQ DX, 0x110(CX)
  :0                    0x4e62db                7e26                    JLE 0x4e6303
  :0                    0x4e62dd                90                      NOPL
  :0                    0x4e62de                bb01000000              MOVL $0x1, BX
  :0                    0x4e62e3                f00fc118                LOCK XADDL BX, 0(AX)
  :0                    0x4e62e7                ffc3                    INCL BX
  :0                    0x4e62e9                0fbae300                BTL $0x0, BX
  :0                    0x4e62ed                733a                    JAE 0x4e6329
  :0                    0x4e62ef                90                      NOPL
  :0                    0x4e62f0                bb01000000              MOVL $0x1, BX
  :0                    0x4e62f5                f00fc118                LOCK XADDL BX, 0(AX)
  :0                    0x4e62f9                ffc3                    INCL BX
  :0                    0x4e62fb                0fbae300                BTL $0x0, BX
  :0                    0x4e62ff                73d0                    JAE 0x4e62d1

After this CL:
  :0                    0x4e6361                48ffc2                  INCQ DX
  :0                    0x4e6364                48399110010000          CMPQ DX, 0x110(CX)
  :0                    0x4e636b                7e26                    JLE 0x4e6393
  :0                    0x4e636d                90                      NOPL
  :0                    0x4e636e                bb01000000              MOVL $0x1, BX
  :0                    0x4e6373                f00fc118                LOCK XADDL BX, 0(AX)
  :0                    0x4e6377                ffc3                    INCL BX
  :0                    0x4e6379                0fbae300                BTL $0x0, BX
  :0                    0x4e637d                733a                    JAE 0x4e63b9
  :0                    0x4e637f                90                      NOPL
  :0                    0x4e6380                bb01000000              MOVL $0x1, BX
  :0                    0x4e6385                f00fc118                LOCK XADDL BX, 0(AX)
  :0                    0x4e6389                ffc3                    INCL BX
  :0                    0x4e638b                0fbae300                BTL $0x0, BX
  :0                    0x4e638f                73d0                    JAE 0x4e6361

PiperOrigin-RevId: 329754148
 2020-09-02 11:37:31 -07:00
Ghanan Gowripalan 9c32fd3f4d Do not copy sleep.Waker 
sleep.Waker's fields are modified as values.

PiperOrigin-RevId: 320873451
 2020-07-12 17:22:08 -07:00
Rahat Mahmood 49d2cf287d Remove implicit dependencies for leaf packages. 
These packages don't actually use go_stateify or go_marshal, but end
up implicitly dependent on the respective packages due to our build
rules.

These unnecessary dependencies make them unusuable in certain contexts
due to circular dependency.

PiperOrigin-RevId: 312595738
 2020-05-20 18:35:32 -07:00
Jamie Liu 30388ff591 Rename files in //pkg/sync to better reflect what they contain. 
PiperOrigin-RevId: 304447031
 2020-04-02 11:57:06 -07:00
Adin Scannell d29e59af9f Standardize on tools directory. 
PiperOrigin-RevId: 291745021
 2020-01-27 12:21:00 -08:00
Ian Gudger 1effdc091b TMutex based on sync.Mutex. 
Updates #231

PiperOrigin-RevId: 290854399
 2020-01-21 18:49:28 -08:00
Ian Gudger 27500d529f New sync package. 
* Rename syncutil to sync.
* Add aliases to sync types.
* Replace existing usage of standard library sync package.

This will make it easier to swap out synchronization primitives. For example,
this will allow us to use primitives from github.com/sasha-s/go-deadlock to
check for lock ordering violations.

Updates #1472

PiperOrigin-RevId: 289033387
 2020-01-09 22:02:24 -08:00
Michael Pratt fe1369ac98 Move package sync to third_party 
PiperOrigin-RevId: 231889261
Change-Id: I482f1df055bcedf4edb9fe3fe9b8e9c80085f1a0
 2019-01-31 17:49:14 -08:00
Michael Pratt 2a0c69b19f Remove license comments 
Nothing reads them and they can simply get stale.

Generated with:
$ sed -i "s/licenses(\(.*\)).*/licenses(\1)/" **/BUILD

PiperOrigin-RevId: 231818945
Change-Id: Ibc3f9838546b7e94f13f217060d31f4ada9d4bf0
 2019-01-31 11:12:53 -08:00
Jamie Liu 8e729e0e1f Add //pkg/sync:generic_atomicptr. 
PiperOrigin-RevId: 215620949
Change-Id: I519da4b44386d950443e5784fb8c48ff9a36c5d3
 2018-10-03 13:52:15 -07:00
Zhaozhong Ni be7fcbc558 stateify: support explicit annotation mode; convert refs and stack packages. 
We have been unnecessarily creating too many savable types implicitly.

PiperOrigin-RevId: 206334201
Change-Id: Idc5a3a14bfb7ee125c4f2bb2b1c53164e46f29a8
 2018-07-27 10:17:21 -07:00
Googler d02b74a5dc Check in gVisor. 
PiperOrigin-RevId: 194583126
Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463
 2018-04-28 01:44:26 -04:00