Date: Mon, 03 Jan 2005 20:40:45 +0100 From: =?ISO-8859-1?Q?S=F8ren_Schmidt?= <sos@DeepCore.dk> To: Nate Lawson <nate@root.org> Cc: FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: ATA rman performance enhancement Message-ID: <41D99FBD.8070500@DeepCore.dk> In-Reply-To: <41D984A5.7010408@root.org> References: <41D984A5.7010408@root.org>
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Nate Lawson wrote: > While doing some benchmarking of other code, I noticed that there were a > lot of calls to rman_get_bustag/handle(). They weren't taking up much > actual time since they're pretty lightweight but seemed to be unnecessary. > > I worked up the attached diff and benchmarked it. There are about 1000 > calls a second to the rman routines without this patch and essentially > none with it. It makes about a 1% difference in throughput under some > IO loads. It is only for non-Promise or non-SII controllers right now > since I didn't extend the initialization step to more than ata-pci.c. > The same approach could be used for the other INW/OUTW calls as well but > they're not in the fast path. I think it may make more of a difference > with small reads. > > Feel free to test, cleanup, and commit. I had something semilar to this once back when, but since HW got lots faster I couldn't measure it anymore, but maybe things has changed... Anyhow it needs to be applied to ata-isa.c ata-card.c ata-cbus.c etc to not break anything at least. I'll think about it and eventually do something about it in ATA-mkIII if it really is mesureable again.. -- -Søren
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