Date: Thu, 29 Nov 2012 23:31:26 +0200 From: Andriy Gapon <avg@FreeBSD.org> To: Nikolay Denev <ndenev@gmail.com> Cc: freebsd-stable@FreeBSD.org Subject: Re: ZFS memory management Message-ID: <50B7D42E.9010904@FreeBSD.org> In-Reply-To: <D0B12906-2E5A-4CD5-B7E3-78EB7CD04A4C@gmail.com> References: <7A88B836-C985-446C-A992-A295A2474A38@gmail.com> <CAOjFWZ4MsOmOEXuO8pzMKqN3_ykA7i=jkcMYxPT-6xdWVerfsw@mail.gmail.com> <CABzXLYOuVGX1wPuHMq8LAn=d%2BeVsjRDtfLt-2X-D_=ChAztG-w@mail.gmail.com> <D0B12906-2E5A-4CD5-B7E3-78EB7CD04A4C@gmail.com>
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on 29/11/2012 19:16 Nikolay Denev said the following: > > On Nov 29, 2012, at 4:53 PM, Olivier Smedts <olivier@gid0.org> wrote: > >> 2012/11/27 Freddie Cash <fjwcash@gmail.com>: >>> Read any ZFS tuning manual on the web, including the ones direct from >>> SUN/Oracle, and they all list: >>> - if you are running processes that need a lot of memory, then limit the >>> ARC to allow the apps to have access to that memory >> >> Or you could have at least a little swap (good practice) to allow ARC >> take the time to evict some memory when under pressure. >> > > Yes, this was already suggested off-list, and it seems like a solution. > > Thanks to all for the input! I think that various VM thresholds are not very well auto-tuned for a swap-less system. So, perhaps, something to _experiment_ with... I could make sense to increase (e.g. double or triple) vm.v_cache_min, so that the pager is waken up earlier. At the same time vm.v_free_target could be decreased so that difference between it and vm.v_free_reserved is smaller (but greater than zero). My understanding is that OOM handling is activated when the pager can not get number of available (free + cached) pages above v_cache_min + v_free_target after two passes. -- Andriy Gapon
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