Messages in this thread |  | | Date | Tue, 6 May 2003 21:17:55 +0530 | From | Dipankar Sarma <> | Subject | Re: 2.5.69-mm1 |
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On Tue, May 06, 2003 at 07:20:51AM -0700, David S. Miller wrote: > From: Dipankar Sarma <dipankar@in.ibm.com> > > Provided there isn't a very heavy contention among readers for the > spin_lock. > > Even if there are thousands of readers trying to get the lock > at the same time, unless your hold time is significant these > readers will merely thrash the cache getting the rwlock_t. > And then thrash it again to release the rwlock_t.
And now ISTR that this is indeed the case, atleast going by what we saw with "chat" microbenchmarks (fwiw :)). Hold times weren't very high and most of the performance penalty came from bouncing of the rwlock cacheline, which prompted us to write a RCU-based patch for lockfree lookup from fd table.
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