Date: Fri, 16 Sep 2005 21:51:21 +0530 From: Joseph Koshy <joseph.koshy@gmail.com> To: Oliver Lehmann <lehmann@ans-netz.de> Cc: current@freebsd.org Subject: Re: low(er) disk performance with sched_4bsd then with sched_ule Message-ID: <84dead720509160921732e7f96@mail.gmail.com> In-Reply-To: <20050915181238.54b16b4b.lehmann@ans-netz.de> References: <20050914194612.15692485.lehmann@ans-netz.de> <43286E37.40203@samsco.org> <20050914222013.178dc4dc.lehmann@ans-netz.de> <84dead72050914135239514c49@mail.gmail.com> <20050915000053.448f251b.lehmann@ans-netz.de> <84dead7205091500152a7c25d1@mail.gmail.com> <20050915172005.072f4bdf.lehmann@ans-netz.de> <20050915181238.54b16b4b.lehmann@ans-netz.de>
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jk> What happens if you use a kernel with 'options=20 jk> NO_ADAPTIVE_MUTEXES' ? ol> Hmm, that made it more worse ol> http://pofo.de/tmp/gprof.4bsd.2 >From the profile it appears that with adaptive mutexes turned off the kernel is spinning inside vm_pageout(). 41.1 vm_pageout [1] 25.0 _mtx_trylock [2] 5.1 smp_tlb_shootdown [3] Hmm ... the dd command line *did* ask for about approx 2 GB of zero-filled memory from the kernel while the machine has about 640M. I'm just not able to reproduce this kind of skewed profile on -current on a uniprocessor amd64 and on a P4 HT machine. Just as an off-chance: how upto-date is your kernel? In=20 particular, do you have the following fix:=20 "sys/vm/vm_pager.c:" revision 1.105.2.1 date: 2005/08/15 14:04:47; author: kan; state: Exp; lines: +1 -0 MFC: Do not use vm_pager_init() to initialize=20 vnode_pbuf_freecnt variable. vm_pager_init() is run before=20 required nswbuf variable has been set to correct value. This=20 caused system to run with single pbuf available for=20 vnode_pager. Handle both cluster_pbuf_freecnt and=20 node_pbuf_freecnt variableis in the same way. --=20 FreeBSD Volunteer, http://people.freebsd.org/~jkoshy
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