Date: Wed, 28 Aug 2013 13:35:52 -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: <1377722152984-5839755.post@n5.nabble.com> In-Reply-To: <kvkh1j$7fj$1@ger.gmane.org> References: <521C9E85.4060801@UToledo.edu> <CAE-mSOLCYRM0LRLRgmaEZN1u5ozttJZC3kWtw3Zarqik1N29zw@mail.gmail.com> <521D7552.5080008@UToledo.edu> <kvkh1j$7fj$1@ger.gmane.org>
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>>>> I believe that increasing the following values by 10 would benefit >>>> most FreeBSD users without disadvantage. >>>> >>>> vfs.ufs.dirhash_maxmem: 2097152 to 20971520 >>>> >>>> vfs.ufs.dirhash_reclaimage: 5 to 50 or 60 >>> vfs.ufs.dirhash_maxmem is further autotuned based on available >>> physical memory. >>> See r214359 for details. >>> > > To what value does the algorithm tune in your case? On my 16 GB machine, > it's ~~ 25 MB: > > vfs.ufs.dirhash_maxmem: 26968064 > > The policy is to use fractions of the installed RAM (though in a > roundabout way), so it should scale reasonably well to both systems with > large and small memories. > > I'll bump vfs.ufs.dirhash_reclaimage to 60, it's worth it. I'm running 2 Gigs of RAM, so it sets to 2 Megs. As compiling most of the system uses ~1.5 Gigs, I can certainly use the cache. Note that allocated kernel memory does not scale linearly with physical RAM, so a policy to use fractions of kernel memory may be more appropriate. ~25 Megs is a good value, however, as the reclaim value is a portion of vfs.ufs.dirhash_maxmem, a much larger cache and it becomes pyric as it can keep wiping out a small active cache. (I tested vfs.ufs.dirhash_maxmem up to 60 megs.) -- View this message in context: http://freebsd.1045724.n5.nabble.com/Suggest-changing-dirhash-defaults-for-FreeBSD-9-2-tp5839351p5839755.html Sent from the freebsd-stable mailing list archive at Nabble.com.
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