Date: Mon, 25 Jun 2001 08:25:34 -0400 (EDT) From: Christopher Sedore <cmsedore@mailbox.syr.edu> To: Richard Hodges <rh@matriplex.com> Cc: Josh Osborne <stripes@mac.com>, freebsd-hackers@FreeBSD.ORG Subject: Re: question: aio / nbio / kqueue Message-ID: <Pine.SOL.4.10.10106250822410.3561-100000@rodan.syr.edu> In-Reply-To: <Pine.BSF.4.10.10106221717070.63905-100000@mail.matriplex.com>
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On Fri, 22 Jun 2001, Richard Hodges wrote: > On Fri, 22 Jun 2001, Josh Osborne wrote: > > > On Friday, June 22, 2001, at 07:01 PM, E.B. Dreger wrote: > > > My question is, from a performance standpoint, in what situations are > > > these techniques most appropriate? > > > AIO is good when you are not receiving much data (or not receiving > > it very frequently), and presumably want very low latency. > > What if you want good performance with "moderate" disk IO, say ten > to twenty megabytes per second continuously? > > I tried AIO some months ago (4.1R or 4.2R), but had some trouble > with AIO, mainly that it seemed to lose track of half my files. > Not any particular files, it seemed that at any moment it would > just pick ten or so (out of maybe 20-25 files) to ignore at any > given time. > I've done this at the 3-6 MB/sec continous (peaks at 10MB+/sec) range with good success with aio, both the network and disk functions. Never had trouble with it losing track of files (not sure what you mean here). If you didn't tweak some of the default sysctl settings, you may have bumped limits that caused unexpected behaviour (though you should have gotten error returns to let you know). -Chris To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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