Date: Sun, 13 Feb 2005 17:01:19 -0600 From: Alan Cox <alc@cs.rice.edu> To: Alan Cox <alc@FreeBSD.org> Cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/dev/md md.c Message-ID: <20050213230119.GE10496@cs.rice.edu> In-Reply-To: <200502132151.j1DLpoLO035854@repoman.freebsd.org> References: <200502132151.j1DLpoLO035854@repoman.freebsd.org>
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On Sun, Feb 13, 2005 at 09:51:50PM +0000, Alan Cox wrote: > alc 2005-02-13 21:51:50 UTC > > FreeBSD src repository > > Modified files: > sys/dev/md md.c > Log: > Request a CPU private mapping from sf_buf_alloc(). If the swap-backed > memory disk is larger than the number of available sf_bufs, this improves > performance on SMPs by eliminating interprocessor TLB shootdowns. For > example, with 6656 sf_bufs, the default on my test machine, and a 256MB > swap-backed memory disk, I see the command > "dd if=/dev/md0 of=/dev/null bs=64k" achieve ~489MB/sec with the default, > shared mappings, and ~587MB/sec with CPU private mappings. > > Revision Changes Path > 1.153 +6 -1 src/sys/dev/md/md.c For completeness, I'll add that with a uniprocessor kernel on the same machine, this test achieves a bandwidth of ~827MB/sec. Alan
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