Date: Mon, 6 Feb 2017 16:05:21 +0300 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: Fabian Keil <freebsd-listen@fabiankeil.de> Cc: freebsd-hackers@freebsd.org Subject: Re: Inactive memory Message-ID: <20170206130521.GE5366@zxy.spb.ru> In-Reply-To: <20170206131711.76fe19ed@fabiankeil.de> References: <20170206102159.GD5366@zxy.spb.ru> <20170206131711.76fe19ed@fabiankeil.de>
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On Mon, Feb 06, 2017 at 01:17:11PM +0100, Fabian Keil wrote: > Slawa Olhovchenkov <slw@zxy.spb.ru> wrote: > > > What is 'Inactive' memory? > > From sys/vm/vm_page.h: > /* > * Each pageable resident page falls into one of four lists: > * > * free > * Available for allocation now. > * > * cache > * Almost available for allocation. Still associated with > * an object, but clean and immediately freeable. > * > * The following lists are LRU sorted: > * > * inactive > * Low activity, candidates for reclamation. > * This is the list of pages that should be > * paged out next. > * > * active > * Pages that are "active" i.e. they have been > * recently referenced. > * > */ > > A case-insensitive grep for "inactive" in the directory > will result in a couple of additional relevant comments > and implementation details. > > > Can I let is definitly availably for allocation (after some time)? > > Under some load I am got about 30GB of Inactive memory and I am > > prefer migrate this memory to ARC cache. > > > > Can I have assurance about freeing this memory under pressure? > > While inactive memory is supposed to be freed under memory > pressure, in vanilla FreeBSD the ARC may shrink to relieve > memory pressure first. In extreme case the ARC may shrink > to its limit while the inactive memory continues to grow. > > In ElectroBSD, this patch is supposed to address this: > https://www.fabiankeil.de/sourcecode/electrobsd/ElectroBSD-r312620-6cfa243f1516/0239-sys-vm-Limit-the-inactive-pages-more-aggressively.diff > You could give it a try to see if it helps for your workload. I am afraid this patch. > If you haven't already, you also may want to look at: > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=187594 > Among other things, it contains a bunch of (conflicting) > theories about how the system behaves under memory pressure. I am see some reports (in wild internet) about count as 'inactive' used memory in tmpfs. I am not sure about conversion this pages to free and ack this question. Thanks for URLs, I am try different patch for ARC.
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