Date: Thu, 20 Mar 2014 17:06:07 +0200 From: Andriy Gapon <avg@FreeBSD.org> To: Karl Denninger <karl@denninger.net>, freebsd-fs@FreeBSD.org Subject: Re: kern/187594: [zfs] [patch] ZFS ARC behavior problem and fix Message-ID: <532B03DF.7080503@FreeBSD.org> In-Reply-To: <201403201230.s2KCU1vx057435@freefall.freebsd.org> References: <201403201230.s2KCU1vx057435@freefall.freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
on 20/03/2014 14:30 Karl Denninger said the following: > The following reply was made to PR kern/187594; it has been noted by GNATS. > > From: Karl Denninger <karl@denninger.net> > To: bug-followup@FreeBSD.org, karl@fs.denninger.net > Cc: > Subject: Re: kern/187594: [zfs] [patch] ZFS ARC behavior problem and fix > Date: Thu, 20 Mar 2014 07:26:39 -0500 > > This is a cryptographically signed message in MIME format. > > --------------ms010203060907010901070002 > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > Content-Transfer-Encoding: quoted-printable > > I am increasingly-convinced with increasing runtime now on both=20 > synthetic and real loads in production that the proper default value for = > > vfs.zfs.arc_freepages is vm.stats.vm.v_free_target less "just a bit." =20 > Five percent appears to be ok for most workloads with RAM configurations = How about just changing vm_paging_needed() check to vm_paging_target() > 0 check? Could you please try to test this? > ranging from 4GB to the 24GB area (configurations that I can easily test = > > under both synthetic and real environments.) > > Larger invasions of the free target increasingly risk provocation of the = > > behavior that prompted me to get involved in working this part of the=20 > code in the first place, including short-term (~5-10 second) "stalls"=20 > during which the system appears to be locked up, but is not. > > It appears that the key to avoiding that behavior is to not allow the=20 > ARC to continue to take RAM when a material invasion of that target=20 > space has occurred. -- Andriy Gapon
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?532B03DF.7080503>