Date: Thu, 29 Aug 2013 12:42:39 -0700 (PDT) From: Robert_Burmeister <robert.burmeister@utoledo.edu> To: freebsd-stable@freebsd.org Subject: Re: Suggest changing dirhash defaults for FreeBSD 9.2. Message-ID: <1377805359915-5840115.post@n5.nabble.com> In-Reply-To: <521C9E85.4060801@UToledo.edu> References: <521C9E85.4060801@UToledo.edu>
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After scouring the internet, it seems that no one else has done a great deal of testing of UFS2 dirhash defaults lately. As the dirhash feature has effectively been tested for regressions, I would like to propose setting the default dirhash values to my original recommendation: vfs.ufs.dirhash_maxmem: 20971520 vfs.ufs.dirhash_reclaimage: 60 The last benchmarks from 2008 only tested dirhash_maxmem at 2 and 64 megs. I found in my testing that setting maxmem much over 32 megs makes the UFS dirhash dysfunctional, as scavenging 10% of maxmem on each vm_lowmem event becomes too aggressive. While autotuning defaults is highly desirable, autotuning dirhash_maxmem opens the can of worms of also tuning the hard coded 10% scavenging. It may be better to hard code the maxmem default. It may be appropriate to set the reclaimage to 5 minutes rather than 5 seconds; I consider 60 seconds to still be a very conservative value, but at least an effective one. -- View this message in context: http://freebsd.1045724.n5.nabble.com/Suggest-changing-dirhash-defaults-for-FreeBSD-9-2-tp5839351p5840115.html Sent from the freebsd-stable mailing list archive at Nabble.com.
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