Date: Fri, 14 Oct 2011 12:35:05 +0200 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-fs@freebsd.org Subject: Re: dirhash and dynamic memory allocation Message-ID: <j7938v$66s$1@dough.gmane.org> In-Reply-To: <4E97FEDD.7060205@quip.cz> References: <4E97FEDD.7060205@quip.cz>
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This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig4D4328D43A65108185353101 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 14/10/2011 11:20, Miroslav Lachman wrote: > Hi all, >=20 > I tried some tuning of dirhash on our servers and after googlig a bit, = I > found an old GSoC project wiki page about Dynamic Memory Allocation for= > Dirhash: http://wiki.freebsd.org/DirhashDynamicMemory > Is there any reason not to use it / not commit it to HEAD? AFAIK it's sort-of already present. In 8-stable and recent kernels you can give huge amounts of memory to dirhash via vfs.ufs.dirhash_maxmem (but except in really large edge cases I don't think you *need* more than 32 MB), and the kernel will scale-down or free the memory if not needed. In effect, vfs.ufs.dirhash_maxmem is the upper limit - the kernel will use less and will free the allocated memory in low memory situations (which I've tried and it works). > And second question - is there any negative impact with higher > vfs.ufs.dirhash_maxmem? It stil defaults to 2MB (on FreeBSD 8.2) after Not that I know of. > 10 years, but I think we all are using bigger FS in these days with lot= > of files and directories and 2MB is not enough. AFAIK I've changed it to autotune so it's configured to approximately 4 MB on a 4 GB machine (and scales up) in 9. --------------enig4D4328D43A65108185353101 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk6YEF8ACgkQldnAQVacBcgr/QCeLLxe/5TD3zr4EKC9DGG8dmhC q5oAoPrVCYgrh5bFIl7CwSzEIgc45Ty3 =NAht -----END PGP SIGNATURE----- --------------enig4D4328D43A65108185353101--
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