Re: Fine-grained locking for POSIX local sockets (UNIX domain sockets)

From: Julian Elischer <julian_at_elischer.org>
Date: Tue, 09 May 2006 10:35:06 -0700
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 _at_
>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 _at_
>  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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>
Received on Tue May 09 2006 - 15:35:08 UTC

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