Date: Wed, 15 Feb 2012 17:27:51 +0200 From: George Kontostanos <gkontos.mail@gmail.com> To: Pavlo <devgs@ukr.net> Cc: freebsd-fs@freebsd.org Subject: Re: ZFS and mem management Message-ID: <CA%2BdUSyp1p07ERXaL-zLG4ibGB45c7VGBNH3ALL4ZXbXUbeEDiA@mail.gmail.com> In-Reply-To: <70229.1329318412.9319724204137054208@ffe16.ukr.net> References: <70229.1329318412.9319724204137054208@ffe16.ukr.net>
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2012/2/15 Pavlo <devgs@ukr.net>: > > > >>On 15/02/2012 13:39, Pavlo wrote: >>> > >>> >> >> Unfortunately we can't afford disabling prefetch. It is too much of an>> overhead.>> >> Also I made some tests. I have process that maps file using mmap() and>> writes or reads first byte of each page of mapped file with some data.> >>Note that ZFS is designed so that it interacts somewhat badly with >>mmap() and other kernel services which rely on coherency between VM and >>IO such as sendfile(). At the very best, you will have two in-kernel >>copies of all data buffers used with such interfaces, but there have >>been sporadic reports that there are other bugs with it. >> >>If you have a test server, I'd recommend you do the same test on UFS for >>comparison. > > Was going to try this... Thanks for reply. > _______________________________________________ > 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" Why do you think that disabling prefetch is an overhead? -- George Kontostanos Aicom telecoms ltd http://www.aisecure.net
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