Date: Mon, 12 Sep 2011 21:09:08 +0200 (CEST) From: Laszlo KAROLYI <szoftos@freemail.hu> To: freebsd-fs@freebsd.org Subject: Re: ZFS-lighttpd2-sendfile, too high IO Message-ID: <freemail.20110912210908.38291.2@xmldata09.freemail.hu> In-Reply-To: <alpine.GSO.2.01.1109121356080.12948@freddy.simplesystems.org>
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But does this explain the 4-5mbyte/s reads when having a 15mbit/s network l= oad? Bob Friesenhahn <bfriesen@simple.dallas.tx.us> =EDrta: >On Mon, 12 Sep 2011, K. Macy wrote: > >> 2011/9/12 Steven Hartland <killing@multiplay.co.uk>: >>> sendfile doesn't work as you might expect on zfs, its not zero copy= due to >>> the use of none buffer pool memory. >>> >>> You do get a benefit but it requires double the amount of memory to get= it >>> so we've disabled sendfile >>> under nginx for zfs based hosts for this very reason. >> >> In my performance testing, sending from mmaped I/O on ZFS was >> dramatically faster (> 2x) than sendfile. > >The problem is that since the zfs ARC and the backing memory used for=20 >the mapping are not the same, twice as much memory is used. This=20 >would not be good for streaming if the machine is short on RAM. > >Bob >--=20 >Bob Friesenhahn >bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ >GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ >_______________________________________________ >freebsd-fs@freebsd.org mailing list >http://lists.freebsd.org/mailman/listinfo/freebsd-fs >To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org"
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