Date: Fri, 12 Feb 2010 13:10:51 -0800 From: Artem Belevich <fbsdlist@src.cx> To: Steve Polyack <korvus@comcast.net> Cc: freebsd-fs@freebsd.org, freebsd-stable <freebsd-stable@freebsd.org> Subject: Re: ZFS ARC being limited below what is defined in /boot/loader.conf Message-ID: <ed91d4a81002121310v186f36d3l53f88cc973f5430d@mail.gmail.com> In-Reply-To: <4B75ADC7.6000308@comcast.net> References: <4B759E70.4030809@comcast.net> <ed91d4a81002121047y18c6c627td9a7797164ba050a@mail.gmail.com> <4B75ADC7.6000308@comcast.net>
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vm.kmem_size_max/vm.kmem_size_min define the range vm.kmem_size can be set = to. vm_kmem_size specifies the actual kmem size. ARC size in turn limited by vm.kmem_size. If you want to bump ARC size, you do need to bump vm.kmem_size. --Artem On Fri, Feb 12, 2010 at 11:36 AM, Steve Polyack <korvus@comcast.net> wrote: > On 02/12/10 13:47, Artem Belevich wrote: >> >> On Fri, Feb 12, 2010 at 10:31 AM, Steve Polyack<korvus@comcast.net> >> =A0wrote: >> >> >>> >>> Has anyone had an issue with the ZFS ARC max being limited below what h= as >>> been defined in /boot/loader.conf? =A0I just upgraded the RAM in a >>> ZFS-equipped system and attempted to devote 4GB to the ARC cache by >>> placing >>> the following in loader.conf: >>> =A0vfs.zfs.arc_max=3D"4096M" >>> >>> However, after rebooting, querying the sysctl gives me this: >>> $ sysctl vfs.zfs.arc_max >>> vfs.zfs.arc_max: 1726489600 >>> >>> or about 1.7GB, an odd number that I can't find any references to. =A0F= or >>> reference, I'm running 8-STABLE (as of Jan 19th) on an amd64 system wit= h >>> 8GB >>> of RAM. =A0The system was previously very stable with 4GB of RAM and a >>> 512MB >>> arc_max. =A0I have not modified vm.kmem_size_max (defaults to ~330GB on >>> amd64) >>> or any other ZFS tunables. =A0I'd also like to avoid syncing up to the >>> current >>> 8-STABLE if at all possible. >>> >>> Thanks, >>> Steve Polyack >>> >>> _______________________________________________ >>> freebsd-stable@freebsd.org mailing list >>> http://lists.freebsd.org/mailman/listinfo/freebsd-stable >>> To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.or= g" >>> >>> >> >> Check your vm.kmem_size. Default setting is way too low. Set it to at >> least double of desired arc size. >> >> --Artem > > I mentioned it briefly, but vm.kmem_size_max was left at the default for > amd64. =A0At 330GB it is way above and beyond what will ever be allocated= to > ARC: > $ sysctl vm.kmem_size_max > vm.kmem_size_max: 329853485875 > > >
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