Date: Mon, 30 Dec 2002 22:13:16 +1100 (EST) From: Bruce Evans <bde@zeta.org.au> To: phk@FreeBSD.org Cc: cvs-committers@FreeBSD.org, <cvs-all@FreeBSD.org> Subject: Re: cvs commit: src/sys/sys _mutex.h Message-ID: <20021230220721.Y46191-100000@gamplex.bde.org> In-Reply-To: <3507.1041241745@critter.freebsd.dk>
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On Mon, 30 Dec 2002 phk@FreeBSD.org wrote: > In message <20021230142740.R44529-100000@gamplex.bde.org>, Bruce Evans writes: > >On Sun, 29 Dec 2002, Poul-Henning Kamp wrote: > > > >> phk 2002/12/29 03:14:41 PST > >> > >> Modified files: > >> sys/sys _mutex.h > >> Log: > >> Save 16 bytes per mutex if MUTEX_PROFILING is not defined. > >> > >> MUTEX_PROFILING is in opt_global.h, so this does not introduce a risk of > >> variant structure sizes unless foreign kernel modules are used. > > > >Not so. This breaks all modules, not just foreign ones, since > >opt_global.h is not included in any module, and even if it were then > >its setting for some modules might differ from the setting in the > >kernel. > > Ok, we should make MUTEX_PROFILING an undocumented option then. No, we should put it back like it was or implement it in out-of-band storage. > A cost of 16 bytes per mutex is not warranted for a "only once in > a blue moon" option. This can be considered a feature. It inhibits use of thousands, if not hundreds of thousands of locks. Another hack would be to make it the default for modules like many other options. This could be considered a feature. It rewards use of modules with another pessimization. Bruce To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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