Fine-grained locking for POSIX local sockets (UNIX domain
sockets)
Kris Kennaway
kris at obsecurity.org
Sun May 7 19:16:55 UTC 2006
On Sun, May 07, 2006 at 10:00:41PM +0300, Sven Petai wrote:
> The results in my mail were mean values over 2 runs,
> only once did I see really huge (more than 10%) differences between several
> subsequent runs with same settings, this case was clearly mentioned in the results.
FYI, 2 is not really enough, you should do at least 10 repetitions of
each test to reduce variance (which can be a lot, despite what you
saw!) and so that differences between them can be accurately
estimated. Ministat is really helpful for this.
> most contended locks:
> max total count avg cnt_hold cnt_lock name
> 8143 926138412 36000820 25 111228313 34861067 /usr/src/sys/kern/uipc_usrreq.c:309 (unp)
> 9 1359 223 6 167 31657721 /usr/src/sys/kern/uipc_usrreq.c:709 (unp)
> 6107 123376889 4000519 30 12373564 3900209 /usr/src/sys/kern/uipc_usrreq.c:364 (unp)
> 34045 553265364 7972969 69 3951680 3101074 /usr/src/sys/kern/kern_descrip.c:378 (Giant)
> 1893100 355809996 44119592 8 602861 927204 /usr/src/sys/kern/kern_descrip.c:2011 (filedesc structure)
> 807479 389358045 44119592 8 1399635 853369 /usr/src/sys/kern/kern_descrip.c:1990 (filedesc structure)
> 146 1629 86 18 28 544914 /usr/src/sys/kern/kern_conf.c:311 (Giant)
> 991109 37883055 8003082 4 615328 509225 /usr/src/sys/kern/kern_descrip.c:385 (filedesc structure)
> 33986 33267790 7972969 4 244622 405542 /usr/src/sys/kern/kern_descrip.c:438 (filedesc structure)
> 13 16943 5357 3 475 381640 /usr/src/sys/kern/sys_generic.c:691 (filedesc structure)
Another patch that helps a lot (gets rid of the Giant in the above
trace and gives me a modest performance boost) is here:
http://people.freebsd.org/~csjp/kern_descrip.c.1145074052.diff
He hasn't committed it yet because there is some evidence it helps to
make an unrelated devfs bug more common in certain test loads. I've
come to the opinion that it should just be committed since the problem
does not seem to be directly caused by this change.
Kris
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 187 bytes
Desc: not available
Url : http://lists.freebsd.org/pipermail/freebsd-performance/attachments/20060507/68817a04/attachment.pgp
More information about the freebsd-performance
mailing list