Fine-grained locking for POSIX local sockets (UNIX
domain sockets)
Julian Elischer
julian at elischer.org
Tue May 9 17:35:08 UTC 2006
Sven Petai wrote:
are there any patches that take the gettimeofday() calls and replace
them with something that is cheap
such as only doing every 10th one and just returning the last value ++ 1
uSec for the other ones..
a ktrace of Mysql shows a LOT of gettimeofday() calls.
>On Tuesday 09 May 2006 03:42, Kris Kennaway wrote:
>
>
>>On Tue, May 09, 2006 at 03:34:59AM +0300, Sven Petai wrote:
>>
>>
>>>>Hmm, with this patch mysql 4.1 seems to crash at startup. I haven't
>>>>yet had time to investigate. Is anyone else seeing this?
>>>>
>>>>
>>>Seems to run fine here with 4.1.18 on amd64, but doesn't seem to make
>>>much difference though.
>>>
>>>I ran the tests again on the 8 core machine with and without rwatsons
>>>patch and this time with 6 tests for each setting and generated graphs:
>>>http://bsd.ee/~hadara/debug/mysql4/stats.html
>>>
>>>thr + select smack dynamics with the patch really do look quite
>>>interesting
>>>
>>>PS
>>>I'm currently running testround with rwatsons patch +
>>>http://people.freebsd.org/~csjp/kern_descrip.c.1145074052.diff + mysqld
>>>change davidxu suggested.
>>>Are there any other patches out there that I should try ?
>>>
>>>
>>Sorry, I meant
>>http://people.freebsd.org/~csjp/sys.mpsafe.fileops.1145896495.diff
>>instead of that patch. Also try turning down HZ to 100, and changing
>>the wakeup()s to wakeup_one() in sys/filedesc.h.
>>
>>
>
>I preformed additional tests with the settings you suggested,
>updated graphs are available @
>http://bsd.ee/~hadara/debug/mysql4/stats.html
>
> * with rwatsons patch + mysqld change suggested by davidxu +
> http://people.freebsd.org/~csjp/sys.mpsafe.fileops.1145896495.diff
> there doesnt seem to be much difference, but in general things seem to be
>couple of percent better
> mutex profiles for this configuration are available @
> with 10 smack threads:
>http://bsd.ee/~hadara/debug/mysql4/freebsd_cur_ps2/mutex_freebsd_cur2_p2-select_10_10000.txt
> with 100 smack threads:
>http://bsd.ee/~hadara/debug/mysql4/freebsd_cur_ps2/mutex_freebsd_cur_p2-select_100_1000.txt
>
> * second run was with same patches, but HZ set to 100
> this helps performance a lot but creates large fluxuations in select results
>with >20 threads + thr, sometimes difference between 2 runs with same
>settings was 10000+ q/s
>
>I'm currently still testing wakeup() -> wakeup_one() suggestion.
>
>In addition I did full testrun on linux to see how much this hardware
>is really capable of... graphs for that are available on the stats page too.
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