Date: Thu, 28 Apr 2011 19:13:17 -0700 From: Artem Belevich <art@freebsd.org> To: Jeremy Chadwick <freebsd@jdc.parodius.com> Cc: freebsd-stable List <freebsd-stable@freebsd.org> Subject: Re: ZFS vs OSX Time Machine Message-ID: <BANLkTinntrhiKOwaryZNBuf_qt=6kS5oQA@mail.gmail.com> In-Reply-To: <20110429010829.GA36744@icarus.home.lan> References: <537A8F4F-A302-40F9-92DF-403388D99B4B@gsoft.com.au> <20110428195601.GA31807@icarus.home.lan> <AF725CFF-86A4-4D65-A26E-496F6B9BD33E@gsoft.com.au> <20110429010829.GA36744@icarus.home.lan>
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On Thu, Apr 28, 2011 at 6:08 PM, Jeremy Chadwick <freebsd@jdc.parodius.com> wrote: > I will note something, however: your ARC max is set to 3072MB, yet Wired > is around 4143MB. =A0Do you have something running on this box that takes > up a lot of RAM? =A0mysqld, etc..? =A0I'm trying to account for the "extr= a > gigabyte" in Wired. =A0"top -o res" might help here, but we'd need to see > the process list. > > I'm thinking something else on your machine is also taking up Wired, > because your arcstats shows: > >> kstat.zfs.misc.arcstats.c: 3221225472 >> kstat.zfs.misc.arcstats.c_min: 402653184 >> kstat.zfs.misc.arcstats.c_max: 3221225472 >> kstat.zfs.misc.arcstats.size: 3221162968 > > Which is about 3072MB (there is always some degree of variance). The difference is probably due to fragmentation (most of ARC allocations are served from power-of-2 zones, if I'm not mistaken) + a lot of wired memory sits in slab allocator caches (FREE column in vmstat -z). On a system with ARC size of ~16G I regularly see ~22GB wired. Ona smaller box I get about 7GB wired at around 5.5GB ARC size. --Artem
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