Date: Sun, 25 Nov 2007 10:47:37 +0100 From: Max Laier <max@love2party.net> To: Darren Reed <darrenr@freebsd.org> Cc: freebsd-net@freebsd.org, freebsd-current@freebsd.org, Robert Watson <rwatson@freebsd.org> Subject: Re: Switch pfil(9) to rmlocks Message-ID: <200711251047.44778.max@love2party.net> In-Reply-To: <47491532.1050600@freebsd.org> References: <200711231232.04447.max@love2party.net> <200711242006.04753.max@love2party.net> <47491532.1050600@freebsd.org>
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--nextPart10973900.OHRaPakIth Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline On Sunday 25 November 2007, Darren Reed wrote: > Max Laier wrote: > > On Friday 23 November 2007, Robert Watson wrote: > > > On Fri, 23 Nov 2007, Max Laier wrote: > > > > attached is a diff to switch the pfil(9) subsystem to rmlocks, > > > > which are more suited for the task. I'd like some exposure > > > > before doing the switch, but I don't expect any fallout. This > > > > email is going through the patched pfil already - twice. > > > > > > Max, > > > > > > Have you done performance measurements that show rmlocks to be a > > > win in this scenario? I did some patchs for UNIX domain sockets to > > > replace the rwlock there but it appeared not to have a measurable > > > impact on SQL benchmarks, presumbaly because the read/write blend > > > wasn't right and/or that wasnt a significant source of overhead in > > > the benchmark. I'd anticipate a much more measurable improvement > > > for pfil, but would be interested in learning how much is seen? > > > > I had to roll an artificial benchmark in order to see a significant > > change (attached - it's a hack!). > > > > Using 3 threads on a 4 CPU machine I get the following results: > > null hook: ~13% +/- 2 > > mtx hook: up to 40% [*] > > rw hook: ~5% +/- 1 > > rm hook: ~35% +/- 5 > > Is that 13%/5%/35% faster or slower or improvement or degradation? > If "rw hook" (using rwlock like we have today?) is 5%, whas is the > baseline? > > I'm expecting that at least one of these should be a 0%... Sorry for the sparse explanation. All numbers above are gain with rmlocks= =20 i.e. rmlocks are faster in all scenarios. The test cases are different=20 hook functions. Every hook has a DELAY(1) and a lock/unlock call around=20 it of the respective lock type. read lock acquisitions for rw and rm. =20 Please look at the code I posted a bit later for more details. =2D-=20 /"\ Best regards, | mlaier@freebsd.org \ / Max Laier | ICQ #67774661 X http://pf4freebsd.love2party.net/ | mlaier@EFnet / \ ASCII Ribbon Campaign | Against HTML Mail and News --nextPart10973900.OHRaPakIth Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.4 (FreeBSD) iD8DBQBHSUTAXyyEoT62BG0RAgIyAJ9W1OBtLFLCX/wtiTxnfpOwyo6HeQCdEp+W NTn8ZfHcfE6DDb4oDvJZAmQ= =6v2D -----END PGP SIGNATURE----- --nextPart10973900.OHRaPakIth--
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