Date: Tue, 12 May 2009 18:59:49 +0200 From: Ed Schouten <ed@80386.nl> To: Jeff Roberson <jroberson@jroberson.net> Cc: arch@freebsd.org Subject: Re: lockless file descriptor lookup Message-ID: <20090512165949.GF58540@hoeg.nl> In-Reply-To: <alpine.BSF.2.00.0905111720280.981@desktop> References: <alpine.BSF.2.00.0905111720280.981@desktop>
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--GCRJOSQGwEYxR+j1 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hello Jeff, * Jeff Roberson <jroberson@jroberson.net> wrote: > Once the file descriptor is resolved, we verify the path via the =20 > descriptor table once more to ensure that it has not changed. At this = =20 > point, we have a valid reference or we drop an invalid reference and =20 > retry. It's nice to see someone stepped up to implement this. Just out of curiosity, have you done any benchmarks to see how many percent of the time a thread needs more than one attempt to obtain a valid reference on a common workload? Maybe it would be nice for diagnostic purposes to add two sysctls to obtain the amount of successful and unsuccessful attempts. --=20 Ed Schouten <ed@80386.nl> WWW: http://80386.nl/ --GCRJOSQGwEYxR+j1 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (FreeBSD) iEYEARECAAYFAkoJqwUACgkQ52SDGA2eCwWFFgCfX+ZV7n/CbAGIx9OhQSQNqE73 KnYAniCy0fesWrS7ByA/efWM/gKrF3nT =WnZE -----END PGP SIGNATURE----- --GCRJOSQGwEYxR+j1--
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