Clint Adams wrote:
On Mon, Sep 03, 2007 at 11:23:22PM -0700, Howard Chu wrote:
The test I used most recently was to run test008 in the OpenLDAP test suite
and average the runtimes over 5-10 runs for each BDB version. In my tests I
ran with SLAPD_DEBUG=0 so the only I/O traffic is from BDB and not from
debug logging. I also ran with an extremely small cachesize setting (5, the
default is 1000) to further aggravate the locking contention in the
underlying DB. Under normal conditions (where the cache is not so
ridiculously undersized for the workload) the differences are not as
apparent.
Also note that the runtimes for this test are non-deterministic since they
are affected by deadlock retries, and their pattern is unpredictable on
most systems.
Does the hybrid mutex performance fix in db 4.6.21 solve this problem?
I haven't tested 4.6.21 yet. Looking at the diff from 4.6.19 I see they simply
inserted a yield() into the spinlock loop. I expect that this will introduce
other problems on NPTL systems, since yield()'s behavior is so unfriendly in NPTL.
--
-- Howard Chu
Chief Architect, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc/
Chief Architect, OpenLDAP http://www.openldap.org/project/
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