On Wed, Oct 21, 2009 at 3:04 PM, Michael Widenius <mo...@askmonty.org> wrote:
>
> Hi!
>
>>>>>> "MARK" == MARK CALLAGHAN <mdcal...@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
oltp-ro run again for maria.nostat
761 1278 2593 4406 4207 4164 maria.nostat
>
> <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
simple-allcols re-run for maria.nostat
12024 23891 50433 93778 88210 86127 maria.nostat
So it looks like the regression at --num_threads==1 is real.
I am trying without success to get oprofile results for maria.nostat.
I have them for 5138pi. I don't know why I can't get them for maria --
configure and compiler options appear to be the same, symbols appear
to be there, ... bizarre.
>
> 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.
5138pi is not running with userstats enabled. It is 5.1.38 + InnoDB
1.0.4 plugin with a few patches.
--
Mark Callaghan
mdcal...@gmail.com
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