Date: Sun, 29 Jan 2006 01:35:39 -0700 From: Scott Long <scottl@samsco.org> To: Nate Lawson <nate@root.org> Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, Scott Long <scottl@FreeBSD.org>, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/vm vm_contig.c Message-ID: <43DC7E5B.9080906@samsco.org> In-Reply-To: <43DC7DEB.7050200@root.org> References: <20060129082512.6EBA116A477@hub.freebsd.org> <43DC7DEB.7050200@root.org>
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Nate Lawson wrote: > Scott Long wrote: > >> 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. > > > Interesting. > >> Index: src/sys/vm/vm_contig.c >> diff -u src/sys/vm/vm_contig.c:1.47 src/sys/vm/vm_contig.c:1.48 >> --- src/sys/vm/vm_contig.c:1.47 Thu Jan 26 05:51:26 2006 >> +++ src/sys/vm/vm_contig.c Sun Jan 29 08:24:54 2006 >> @@ -387,7 +387,9 @@ >> vm_offset_t size; >> vm_paddr_t phys; >> vm_page_t pga = vm_page_array; >> - int i, pass, pqtype, start; >> + static vm_pindex_t np = 0; >> + static vm_pindex_t start = 0; >> + int i, pass, pqtype; > > > What lock protects access to these static variables? > The whole function is serialized by Giant. Scott
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