Date: Fri, 3 Jan 2003 23:38:29 +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: <20030103230420.W3339-100000@gamplex.bde.org> In-Reply-To: <10907.1041590410@critter.freebsd.dk>
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On Fri, 3 Jan 2003 phk@freebsd.org wrote: > In message <20030103212617.K2888-100000@gamplex.bde.org>, Bruce Evans writes: > >On Thu, 2 Jan 2003, Poul-Henning Kamp wrote: > >> MFC: Conditionalize 16 bytes of struct mutex on MUTEX_PROFILING > > > >Please back this out. It is contentious even in -current. Even its > >misleading comment hasn't been fixed. > > I'll await re@'s decision. It is necessary to prevent -current and > 5.0-RELENG machines from running out of kmem_map space and as I > read John, that takes precedence. Really? It should make more than a few percent difference. E.g., it bloats the size of a vnode from 284 to 300 on i386's (6%). This isn't all that small for a struct that has so many instances, but if we cared about the size of a vnode then we wouldn't be using so many mutexes and locks in it. Mutexes without profiling have size 52 on i386's, so using a mutex instead of a simplelock for v_interlock bloats the size of a vnode from 236 to 284 (20%). > I agree that we should probably fix the comment and remove > MUTEX_PROFILING from conf/options to prevent unintended use. That would make it a non-option. Several other options have similar problems. A quick grep in <sys> shows: - the non-option USE_BUFHASH modifies struct buf. - ... - the option DEBUG_LOCKS modifies struct lockmgr and struct vnode. Bruce To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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