Date: Wed, 28 Mar 2012 16:55:22 -0500 (CDT) From: Bob Friesenhahn <bfriesen@simple.dallas.tx.us> To: Rick Macklem <rmacklem@uoguelph.ca> Cc: freebsd-fs@freebsd.org Subject: Re: NFSv3, ZFS, 10GE performance Message-ID: <alpine.GSO.2.01.1203281650280.25475@freddy.simplesystems.org> In-Reply-To: <1023490904.1870197.1332970547582.JavaMail.root@erie.cs.uoguelph.ca> References: <1023490904.1870197.1332970547582.JavaMail.root@erie.cs.uoguelph.ca>
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On Wed, 28 Mar 2012, Rick Macklem wrote: >> >> Hopefully, readahead doesn't kill performance for smaller files.. :-) >> > Well, readaheads only happen if the file is large enough for the readahead > to be before EOF. As such, they just won't happen for small files. The real problem is for applications which do a seek and a new read prior to consuming all the data which is being read ahead on its behalf. This results in read amplification and increased latency for the next seek+read. Bob -- Bob Friesenhahn bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
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