svn commit: r202894 - in head/sys/i386: i386 include

[John Baldwin]

On Tuesday 26 January 2010 12:05:29 pm Ivan Voras wrote:
> 2010/1/26 Alexander Leidinger <Alexander at leidinger.net>:
> >
> > Quoting John Baldwin <jhb at freebsd.org> (from Mon, 25 Jan 2010 07:57:49
> > -0500):
> >
> >> On Saturday 23 January 2010 1:42:28 pm Alan Cox wrote:
> >>>
> >>> Author: alc
> >>> Date: Sat Jan 23 18:42:28 2010
> >>> New Revision: 202894
> >>> URL: http://svn.freebsd.org/changeset/base/202894
> >>>
> >>> Log:
> >>>  Handle a race between pmap_kextract() and pmap_promote_pde().  This race
> >>> is
> >>>  known to cause a kernel crash in ZFS on i386 when superpage promotion is
> >>>  enabled.
> >>>
> >>>  Tested by:    netchild
> >>>  MFC after:    1 week
> >>
> >> Yay!  Should we enable pg_ps by default on i386 now?
> >
> > Data point, the i386 system where I have superpages enabled is a p4 with
> > currently 11 jails active. Some webservers, squid, samba, bind, postfix and
> > a lot of portupgrades (during the last days, I'm updating a jail with a
> > desktop-setup inside). All jails are on ZFS.
> 
> Do you have any method of comparing performance before-and-after?
> There was a thread on some of the mailing lists (stable@/current@?)
> about squid being the pessimal case for superpages.

The thread did not say that superpages made squid slower, rather that due to
the way it forked to execute the log rotation binaries, some superpages were
demoted back to regular pages losing the gain of superpages for those pages.

-- 
John Baldwin