Date: Sat, 18 Aug 2007 17:00:28 +0200 From: Pawel Jakub Dawidek <pjd@FreeBSD.org> To: Alfred Perlstein <alfred@freebsd.org> Cc: freebsd-arch@FreeBSD.org Subject: Re: Lockless uidinfo. Message-ID: <20070818150028.GD6498@garage.freebsd.pl> In-Reply-To: <20070818142337.GW90381@elvis.mu.org> References: <20070818120056.GA6498@garage.freebsd.pl> <20070818142337.GW90381@elvis.mu.org>
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--sgneBHv3152wZ8jf Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Aug 18, 2007 at 07:23:37AM -0700, Alfred Perlstein wrote: > * Pawel Jakub Dawidek <pjd@FreeBSD.org> [070818 05:31] wrote: > > Hi. > >=20 > > The patch below remove per-uidinfo locks: > >=20 > > http://people.freebsd.org/~pjd/patches/uidinfo_lockless.patch >=20 > In uifree() is it ok to manually check the refcount for 0? >=20 > I'm gussing the hashmtx is used as a barrier? Yes, to lookup uidinfo you need to hold uihashtbl_mtx mutex, so once you hold it and ui_ref is 0, noone will be able to reference it, because it has to wait to look it up. --=20 Pawel Jakub Dawidek http://www.wheel.pl pjd@FreeBSD.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am! --sgneBHv3152wZ8jf Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.4 (FreeBSD) iD8DBQFGxwmMForvXbEpPzQRAij1AKD39VFS9BweDqwgf9MRFZ9roIOxGQCgkPvW ekGd4bRXzvLa6EpgqnPzcaE= =PYJc -----END PGP SIGNATURE----- --sgneBHv3152wZ8jf--
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