Date: Sun, 29 Jan 2006 08:24:54 +0000 (UTC) From: Scott Long <scottl@FreeBSD.org> To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/vm vm_contig.c Message-ID: <200601290824.k0T8OtsR034314@repoman.freebsd.org>
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scottl 2006-01-29 08:24:54 UTC FreeBSD src repository Modified files: sys/vm vm_contig.c Log: The change a few years ago of having contigmalloc start its scan at the top of physical RAM instead of the bottom was a sound idea, but the implementation left a lot to be desired. Scans would spend considerable time looking at pages that are above of the address range given by the caller, and multiple calls (like what happens in busdma) would spend more time on top of that rescanning the same pages over and over. Solve this, at least for now, with two simple optimizations. The first is to not bother scanning high ordered pages that are outside of the provided address range. Second is to cache the page index from the last successful operation so that subsequent scans don't have to restart from the top. This is conditional on the numpages argument being the same or greater between calls. MFC After: 2 weeks Revision Changes Path 1.48 +19 -2 src/sys/vm/vm_contig.c
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