Date: Wed, 4 Sep 2019 17:50:52 +0300 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: Andriy Gapon <avg@FreeBSD.org> Cc: Mark Johnston <markj@freebsd.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r351673 - in head: lib/libmemstat share/man/man9 sys/cddl/compat/opensolaris/kern sys/kern sys/vm Message-ID: <20190904145052.GE3953@zxy.spb.ru> In-Reply-To: <8b049a33-e844-1a47-2be1-c267946b8f95@FreeBSD.org> References: <201909012222.x81MMh0F022462@repo.freebsd.org> <79c74018-1329-ee69-3480-e2f99821fa93@FreeBSD.org> <20190903161427.GA38096@zxy.spb.ru> <20190903220106.GB26733@raichu> <8b049a33-e844-1a47-2be1-c267946b8f95@FreeBSD.org>
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On Wed, Sep 04, 2019 at 09:27:00AM +0300, Andriy Gapon wrote: > On 04/09/2019 01:01, Mark Johnston wrote: > > Some of the vm_lowmem eventhandlers probably shouldn't be called each > > time the page daemon scans the inactive queue (every 0.1s under memory > > pressure). ufsdirhash_lowmem and mb_reclaim in particular don't seem > > like they need to be invoked very frequently. We could easily define > > multiple eventhandlers to differentiate between these cases, though. > > My proposal is to run uma_reclaim(UMA_RECLAIM_TRIM) before invoking vm_lowmem. > If that reclaims "enough" memory, then do not call vm_lowmem at all. > > Oh, and I have a related question. > Say, a zone has X items in use and Y items in cache. > After running vm_lowmem the composition changes to X - C and Y + C respectively. > Then we run uma_reclaim(UMA_RECLAIM_TRIM). > Question: is that guaranteed to free at least C items? > I am thinking about a possibility that the zone's workset size is estimated to > be at least X (and maybe even more than X + Y). In that case UMA_RECLAIM_TRIM > won't free those C items, they will stay in the cache. So, it seems like > releasing them was in vain, at least for the immediate reclaim. My goal is uma_reclaim(UMA_RECLAIM_TRIM) reclaim from zone cache up to zone cache working set. Idealy in stable run uma_reclaim(UMA_RECLAIM_TRIM) do nothing and all allocation/free from zone go from/to zone cache. As result uma_reclaim(UMA_RECLAIM_TRIM) work only for rebalance memory consume at working profile change.
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