Date: Tue, 17 Apr 2007 13:43:13 +0200 From: Gary Jennejohn <garyj@jennejohn.org> To: Robert Watson <rwatson@FreeBSD.org> Cc: Maxim Sobolev <sobomax@FreeBSD.org>, Thomas Sparrevohn <Thomas.Sparrevohn@btinternet.com>, freebsd-current@FreeBSD.org, pjd@FreeBSD.org, Joerg t <tjoerg@yahoo.com> Subject: Re: Some comments on ZFS Message-ID: <200704171143.l3HBhDZB008693@peedub.jennejohn.org> In-Reply-To: Message from Robert Watson <rwatson@FreeBSD.org> of "Tue, 17 Apr 2007 10:29:31 BST." <20070417102509.T84174@fledge.watson.org>
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Robert Watson writes: > On Mon, 16 Apr 2007, Maxim Sobolev wrote: > > > Joerg t wrote: > >>> There is something weird - Just ran same test again to see whether it was > > >>> a fluke - it still take 1h12 - however I saw the oppersite of Joerg. The > >>> "systat -vm" Freemem was permently on 2,2GB - this on a 4GB system that > >>> normally shows a 1,2GB - or less after a buildworld. > >> > >>> hmm. Pawel are there tests that can help? > >> > >> also how can we determine the real memory consumption by zfs,arc and his > >> vfs cache share ? > >> > >> how can we precisely instrument zfs ? > > > > The "vmstat -m" will give you precise breakdown of kernel memory usage. > > You'll also want to use "vmstat -z". "-m" captures memory allocated by > kernel malloc(9), which is used for variable-sized objects, or objects that > are irregularly allocated. "-z" captures memory allocated by the kernel zone > > allocator, used for regularly sized and frequently allocated objects. Small > allocations in malloc(9) are actually allocated via fixed size memory buckets > > in the zone allocator, so if looking at "-m" as well, ignore zones who's name > s > consist solely of a number (i.e., "16", which is the 16-byte bucket). > Interestingly enough, I see less memory pressure since switching to ZFS. But I'm not using RAIDZ. Previously ``make buildworld'' would use much more memory, probably for buffer caching. It looks like ZFS doesn't use nearly as much buffer cache as UFS (which may not be a good thing). --- Gary Jennejohn / garyjATjennejohnDOTorg gjATfreebsdDOTorg garyjATdenxDOTde
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