On Wed, 2013-03-20 at 15:55 -0400, Rik van Riel wrote:
> Include lkml in the CC: this time... *sigh*
> ---8<---
>
> This series makes the sysv semaphore code more scalable,
> by reducing the time the semaphore lock is held, and making
> the locking more scalable for semaphore arrays with multiple
> semaphores.
>
> The first four patches were written by Davidlohr Buesso, and
> reduce the hold time of the semaphore lock.
>
> The last three patches change the sysv semaphore code locking
> to be more fine grained, providing a performance boost when
> multiple semaphores in a semaphore array are being manipulated
> simultaneously.
>
> On a 24 CPU system, performance numbers with the semop-multi
> test with N threads and N semaphores, look like this:
>
> vanilla Davidlohr's Davidlohr's + Davidlohr's +
> threads patches rwlock patches v3 patches
> 10 610652 726325 1783589 2142206
> 20 341570 365699 1520453 1977878
> 30 288102 307037 1498167 2037995
> 40 290714 305955 1612665 2256484
> 50 288620 312890 1733453 2650292
> 60 289987 306043 1649360 2388008
> 70 291298 306347 1723167 2717486
> 80 290948 305662 1729545 2763582
> 90 290996 306680 1736021 2757524
> 100 292243 306700 1773700 3059159
>
Some results with semop-multi on my 4 core laptop:
vanilla v3 patchset
threads
10 5094473 10289146
20 5079946 10187923
30 5041258 10660635
40 4942786 10876009
50 5076437 10759434
60 5139024 10797032
70 5103811 10698323
80 5094850 9959675
90 5085774 10054844
100 4939547 9798291
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