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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