go /
go /
dd2074c82acda9b50896bf29569ba290a0d13b03 sync: improve Mutex to allow successive acquisitions
This implementation allows a goroutine to do successive acquisitions
of a mutex even if there are blocked goroutines.
Moreover, it allows a newcomer goroutine to acquire a mutex ahead of
blocked goroutines (that is, it does not enforce FIFO).
On implementation level it's achieved by separating waiter count and
locked flag.
Benchmark results on HP Z600 (2 x Xeon E5620, 8 HT cores, 2.40GHz)
are as follows (with 4631059 "replace Semacquire/Semrelease implementation"
patch applied):
benchmark old ns/op new ns/op delta
sync_test.BenchmarkMutexUncontended 24.10 25.40 +5.39%
sync_test.BenchmarkMutexUncontended-2 12.00 13.00 +8.33%
sync_test.BenchmarkMutexUncontended-4 6.06 6.83 +12.71%
sync_test.BenchmarkMutexUncontended-8 3.63 3.60 -0.83%
sync_test.BenchmarkMutexUncontended-16 2.38 2.49 +4.62%
sync_test.BenchmarkMutex 25.00 26.40 +5.60%
sync_test.BenchmarkMutex-2 231.00 49.00 -78.79%
sync_test.BenchmarkMutex-4 259.00 114.00 -55.98%
sync_test.BenchmarkMutex-8 641.00 110.00 -82.84%
sync_test.BenchmarkMutex-16 1380.00 96.30 -93.02%
sync_test.BenchmarkMutexSlack 24.80 26.20 +5.65%
sync_test.BenchmarkMutexSlack-2 210.00 106.00 -49.52%
sync_test.BenchmarkMutexSlack-4 453.00 119.00 -73.73%
sync_test.BenchmarkMutexSlack-8 1024.00 105.00 -89.75%
sync_test.BenchmarkMutexSlack-16 1291.00 91.90 -92.88%
sync_test.BenchmarkMutexWork 796.00 796.00 +0.00%
sync_test.BenchmarkMutexWork-2 399.00 401.00 +0.50%
sync_test.BenchmarkMutexWork-4 216.00 212.00 -1.85%
sync_test.BenchmarkMutexWork-8 1547.00 196.00 -87.33%
sync_test.BenchmarkMutexWork-16 2754.00 287.00 -89.58%
sync_test.BenchmarkMutexWorkSlack 792.00 800.00 +1.01%
sync_test.BenchmarkMutexWorkSlack-2 430.00 420.00 -2.33%
sync_test.BenchmarkMutexWorkSlack-4 467.00 230.00 -50.75%
sync_test.BenchmarkMutexWorkSlack-8 1860.00 273.00 -85.32%
sync_test.BenchmarkMutexWorkSlack-16 3029.00 294.00 -90.29%
R=rsc
CC=golang-dev
https://golang.org/cl/4631075
1 file changed
