Date: Fri, 12 Feb 2010 14:36:39 -0500 From: Steve Polyack <korvus@comcast.net> To: Artem Belevich <fbsdlist@src.cx> 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: <4B75ADC7.6000308@comcast.net> In-Reply-To: <ed91d4a81002121047y18c6c627td9a7797164ba050a@mail.gmail.com> References: <4B759E70.4030809@comcast.net> <ed91d4a81002121047y18c6c627td9a7797164ba050a@mail.gmail.com>
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On 02/12/10 13:47, Artem Belevich wrote: > On Fri, Feb 12, 2010 at 10:31 AM, Steve Polyack<korvus@comcast.net> wrote: > > >> Has anyone had an issue with the ZFS ARC max being limited below what has >> been defined in /boot/loader.conf? I 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: >> vfs.zfs.arc_max="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. For >> reference, I'm running 8-STABLE (as of Jan 19th) on an amd64 system with 8GB >> of RAM. The system was previously very stable with 4GB of RAM and a 512MB >> arc_max. I have not modified vm.kmem_size_max (defaults to ~330GB on amd64) >> or any other ZFS tunables. I'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.org" >> >> > > 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. At 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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