Date: Fri, 23 Nov 2007 14:43:02 +0100 From: Max Laier <max@love2party.net> To: Robert Watson <rwatson@freebsd.org> Cc: freebsd-net@freebsd.org, freebsd-current@freebsd.org Subject: Re: Switch pfil(9) to rmlocks Message-ID: <200711231443.13353.max@love2party.net> In-Reply-To: <20071123132453.W98338@fledge.watson.org> References: <200711231232.04447.max@love2party.net> <20071123132453.W98338@fledge.watson.org>
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--nextPart2052720.Kae1ot7PxS Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline 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 don't yet, but will see if I can collect some data later today. The=20 main reason for the switch is shortcomings in rwlock's (not)=20 implementation of reader recursion as discussed in -arch "rwlocks,=20 correctness over speed." rmlocks do that correctly, afaiu. Unless an artificial no-op hook is used, I don't expect to see significant= =20 performance gain, however. All current pfil(9) consumer need some form=20 of synchronization of their own, which will probably nullify the gain=20 from rmlocks. =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 --nextPart2052720.Kae1ot7PxS 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) iD8DBQBHRtjxXyyEoT62BG0RAoekAJ9FA1CTVdhUjqjfQj65eAuJ7BoREACfVjrH /BxWSf8Hep0pleUb7ggxYAU= =3vst -----END PGP SIGNATURE----- --nextPart2052720.Kae1ot7PxS--
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