Date: 16 Oct 2001 19:57:32 +0200 From: Dag-Erling Smorgrav <des@ofug.org> To: John Baldwin <jhb@FreeBSD.org> Cc: cvs-all@FreeBSD.ORG, cvs-committers@FreeBSD.ORG, Bruce Evans <bde@zeta.org.au>, Matthew Dillon <dillon@apollo.backplane.com> Subject: Re: cvs commit: src/sys/vm vnode_pager.c Message-ID: <xzpzo6rxyb7.fsf@flood.ping.uio.no> In-Reply-To: <XFMail.011016103432.jhb@FreeBSD.org> References: <XFMail.011016103432.jhb@FreeBSD.org>
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John Baldwin <jhb@FreeBSD.org> writes: > How about turning off INVARIANTS and WITNESS and seeing if it does > better? Witness did become more expensive when I made it work for > reader/writer locks on May 4 as it has to manage a list of lock > instances instead of embedding the list inside the lock object > itself. May 4 is about a month and a half before I started seeing these problems, and the profiling data show that witness code and assertions account for less than 4% of CPU time. Here are some of the pertinent excerpts from the call graph: [2] 88.0 32.31 0.03 1168605 _mtx_unlock_spin_flags <cycle 1> [2] 0.03 0.00 1168605/1720935 _mtx_assert [86] 1168605 witness_unlock <cycle 1> [37] [...] 1168605 _mtx_unlock_spin_flags <cycle 1> [2] 0.00 0.00 16/1046526 mtx_destroy [20] 0.00 0.00 56/1046526 _sx_xunlock [223] 0.00 0.00 139/1046526 _sx_sunlock [152] 14.59 0.02 465448/1046526 _mtx_unlock_flags [8] [37] 0.6 0.20 0.00 1634264 witness_unlock <cycle 1> [37] 68406 witness_lock_list_free <cycle 1> [267] [...] 0.01 0.00 465448/1720935 _mtx_unlock_flags [8] 0.03 0.00 1168605/1720935 _mtx_unlock_spin_flags <cycle 1> [2] [86] 0.1 0.05 0.00 1720935 _mtx_assert [86] Out of 32.31 seconds spent in _mtx_unlock_spin_flags() and its descendents, only about 0.25 seconds were spent in witness and assertion code. DES -- Dag-Erling Smorgrav - des@ofug.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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