Date: Mon, 22 Aug 2005 15:40:39 +0200 From: Andre Oppermann <andre@freebsd.org> To: Dag-Erling =?iso-8859-1?Q?Sm=F8rgrav?= <des@des.no> Cc: arch@freebsd.org, Alexey Dokuchaev <danfe@FreeBSD.org> Subject: Re: fdesc allocation optimization Message-ID: <4309D5D7.C7C76B5B@freebsd.org> References: <20050822100059.GA24626@FreeBSD.org> <863bp25c7t.fsf@xps.des.no>
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Dag-Erling Smørgrav wrote: > > Alexey Dokuchaev <danfe@FreeBSD.org> writes: > > i've been browsing some of dfbsd resources recently, and found this one > > being pretty interesting: > > > > http://leaf.dragonflybsd.org/mailarchive/commits/2005-06/msg00526.html > > > > however, it seemingly did not get attention in our lists. so i am > > wondering if there are work/plans on porting hsu@'s work? i remember > > that at some point we adopted some openbsd-derived algorithm, but since > > matt states that this is "far better algorithm then anything we or > > freebsd thought up before", i figured it worth a look. > > Bollocks. Our current algorithm (which I wrote) is so fast you don't > even notice it's there. It's actually simpler than the OpenBSD code > from which it was inspired, and in theory it should be slower, but I > discovered that the overhead of the "better" algorithm was so high > that it consistently lost to the simpler one for reasonable amounts of > file descriptors (up to about 100,000 per process). > > The source code for the microbenchmark I used, and selected graphs > comparing my code to the previous implementation, are available at > <URL:http://people.freebsd.org/~des/fdbench/>. Wow, impressive! > (the strange artifacts you see on the red graphs are the result of the > file descriptor table overrunning the CPU cache) When did you commit this? Is it only in post 5.0 releases? -- Andre
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