Messages in this thread |  | | Subject | Re: Deadlock on the mm->mmap_sem | Date | Thu, 20 Sep 2001 00:25:40 +0100 | From | David Howells <> |
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Andrea Arcangeli <andrea@suse.de> wrote: > On Wed, Sep 19, 2001 at 07:26:33PM +0100, David Howells wrote: > > > if we go generic then I strongly recommend my version of the generic > > > semaphores is _much_ faster (and cleaner) than this one > > > > Not so:-) Your patch, Andrea, grabs the spinlock far more than is necessary. > > then why your microbenchmarks says my version is much faster?
They don't:
[my rwsem-unfair-2.diff patch] #rds #wrs time : rd granted [spread] wr granted [spread] ==== ==== ===== =================== =================== 1 0 10s: 25384639 [0.008%] 0 [0.000%] 2 0 10s: 8007388 [0.013%] 0 [0.000%] 4 0 10s: 8004833 [0.007%] 0 [0.000%] 0 1 10s: 0 [0.000%] 25717288 [0.009%] 0 4 10s: 0 [0.000%] 2817293 [2.323%] 4 2 10s: 12742523 [0.008%] 114 [5.394%] 30 1 10s: 12739163 [0.002%] 92 [1.739%] 30 15 50s: 63733591 [0.003%] 286 [2.711%]
[Andrea's 00_rwsem-19 patch] #rds #wrs time : rd granted [spread] wr granted [spread] ==== ==== ===== =================== =================== 1 0 10s: 24577938 [0.003%] 0 [0.000%] 2 0 10s: 5631224 [0.016%] 0 [0.000%] 4 0 10s: 5633280 [0.009%] 0 [0.000%] 0 1 10s: 0 [0.000%] 24572785 [0.007%] 0 4 10s: 0 [0.000%] 3444786 [0.091%] 4 2 10s: 8036291 [0.008%] 122 [4.918%] 30 1 10s: 8036490 [0.006%] 89 [1.253%] 30 15 50s: 40200472 [0.001%] 265 [2.717%]
[Unpatched kernel] #rds #wrs time : rd granted [spread] wr granted [spread] ==== ==== ===== =================== =================== 1 0 10s: 30118903 [0.008%] 0 [0.000%] 2 0 10s: 12543737 [0.007%] 0 [0.000%] 4 0 10s: 12543731 [0.006%] 0 [0.000%] 0 1 10s: 0 [0.000%] 28408147 [0.008%] 0 4 10s: 0 [0.000%] 1554495 [0.172%] 4 2 10s: 1119656 [0.076%] 560020 [0.077%] 30 1 10s: 5361923 [0.024%] 55787 [0.012%] 30 15 50s: 5322473 [0.049%] 2661621 [0.050%]
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