Date: Fri, 12 Feb 2010 18:47:22 -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: <4B75E88A.1050300@comcast.net> In-Reply-To: <ed91d4a81002121310v186f36d3l53f88cc973f5430d@mail.gmail.com> References: <4B759E70.4030809@comcast.net> <ed91d4a81002121047y18c6c627td9a7797164ba050a@mail.gmail.com> <4B75ADC7.6000308@comcast.net> <ed91d4a81002121310v186f36d3l53f88cc973f5430d@mail.gmail.com>
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This was indeed the issue. I read your first response incorrectly. Thanks a bunch! On 2/12/2010 4:10 PM, Artem Belevich wrote: > 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> >>> 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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