Hi!
"MARK" == MARK CALLAGHAN <mdcallag@gmail.com> writes:
MARK> This includes results from sysbench for Maria 5.2 with/without MARK> userstat enabled and for several other binaries. The results are MARK> throughput (transactions per second) for 1, 2, 4, 8, 16, 32 concurrent MARK> sessions. MARK> ------------ MARK> This tests many binaries including 5.0.37 with the v2 Google patch (aka 5037v2). MARK> On a configuration I no longer have access to, 5037v2 had a severe performance MARK> regression from code in the SHOW [TABLE|USER|_STATISTICS patch. The regression MARK> was caused by mutex contention. The result on my current platform is MARK> much less severe, MARK> but you can see the impact in simple-allcols and simple-handler listed below MARK> -- compare 5037, 5037v2 and 5037v4. MARK> I am using glibc 2.5 now and used an older glibc version in the past. I am MARK> curious if pthread code is that much better on my current platform. MARK> I thought that the Maria version of that feature would inherit this performance MARK> problem. Performance loss in Maria is 5% to 10% with userstat enabled for MARK> high levels of concurrency -- again see results for simple-allcols and MARK> simple-handle -- and this is much less than the loss in 5037v2, but more MARK> than the loss in 5037v4 which had fixes for user and table stats code. Thanks a lot for the numbers! Shows just that things are as you suspected. MARK> oltp-ro MARK> 1 2 4 8 16 32 MARK> concurrent_sessions / binary <cut> MARK> 780 1362 2590 4287 4193 4096 5138pi MARK> 703 1425 2593 4379 4176 4110 maria.nostat MARK> 684 1281 2439 4064 3896 3882 maria.stat <cut> MARK> simple-allcols MARK> 1 2 4 8 16 32 MARK> concurrent_sessions / binary <cut> MARK> 14797 24481 48254 92323 87722 86436 5138pi MARK> 13418 24980 49777 94425 88083 86854 maria.nostat MARK> 13062 23378 46636 83449 77714 77245 maria.stat Do you have any explanation why maria.nostat would be slower than 5138pi ? I can't think of anything in MariaDB that could cause that kind of overhead, especially if 5138pi is running with userstats enabled. Hakan, can you add to your TODO to do a test between MariaDB 5.1 and MariaDB 5.2 and check if there is any performance degradation with Mark's test when userstat is not enabled? Regards, Monty