Date: Sat, 29 Nov 2003 06:11:36 +0100 From: des@des.no (Dag-Erling =?iso-8859-1?q?Sm=F8rgrav?=) To: Tim Robbins <tjr@freebsd.org> Cc: current@freebsd.org Subject: Re: Port of Niels Provos's file descriptor allocation code Message-ID: <xzpr7zrwygn.fsf@dwp.des.no> In-Reply-To: <xzp7k1j9avv.fsf@dwp.des.no> (Dag-Erling =?iso-8859-1?q?Sm=F8rgrav's?= message of "Sat, 29 Nov 2003 03:17:08 %2B0100") References: <20031127070239.GA12950@wombat.robbins.dropbear.id.au> <xzpvfp4816m.fsf@dwp.des.no> <20031129011658.GA1347@wombat.robbins.dropbear.id.au> <xzp7k1j9avv.fsf@dwp.des.no>
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I've run some benchmarks of my own with and without the patch, and it's a definite improvement... I expected it to go linear for large number of open file descriptors, and it does, but the slope is much less steep than I expected, which explains why it looked like O(1). I have two objections to the patch, however: the first is the use of NDENTRYSHIFT to obfuscate multiplications and divisions by NDENTRIES (which is a constant, so the compiler will optimize it anyway). The second is the use of uint32_t instead of unsigned long which should be more efficient on 64-bit machines (NDENTRIES would have to be made dependent on sizeof(unsigned long)) and it scares me a bit that the Banga & Mogul paper has been floating around for five years and nobody took any notice... DES --=20 Dag-Erling Sm=F8rgrav - des@des.no
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