Date: Tue, 25 Sep 2007 13:35:08 +0200 From: Andre Oppermann <andre@freebsd.org> To: Alan Cox <alc@FreeBSD.org> Cc: cvs-src@FreeBSD.org, src-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/amd64/include vmparam.h src/sys/arm/include vmparam.h src/sys/i386/include vmparam.h src/sys/ia64/include vmparam.h src/sys/kern kern_exec.c vfs_bio.c src/sys/powerpc/include vmparam.h src/sys/sparc64/include ... Message-ID: <46F8F26C.50709@freebsd.org> In-Reply-To: <200709250625.l8P6P7w7082233@repoman.freebsd.org> References: <200709250625.l8P6P7w7082233@repoman.freebsd.org>
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Alan Cox wrote: > alc 2007-09-25 06:25:07 UTC > > FreeBSD src repository > > Modified files: > sys/amd64/include vmparam.h > sys/arm/include vmparam.h > sys/i386/include vmparam.h > sys/ia64/include vmparam.h > sys/kern kern_exec.c vfs_bio.c > sys/powerpc/include vmparam.h > sys/sparc64/include vmparam.h > sys/sun4v/include vmparam.h > sys/sys vmmeter.h > sys/vm vm_contig.c vm_fault.c vm_map.c > vm_object.c vm_object.h vm_page.c > vm_page.h vm_pageout.c vm_pageq.c > vm_phys.c vm_phys.h > Log: > Change the management of cached pages (PQ_CACHE) in two fundamental > ways: > > (1) Cached pages are no longer kept in the object's resident page > splay tree and memq. Instead, they are kept in a separate per-object > splay tree of cached pages. However, access to this new per-object > splay tree is synchronized by the _free_ page queues lock, not to be I do not claim to have any specific VM knowledge or about the access pattern on these trees. What I've found however is that in most cases splay trees are massive cache busters due to re-balancing on every access (not just on every insert). The only exception is in cases where a very narrow working set out of a larger number of objects in tree is in high use. Otherwise red-black trees or for some sets hashes tend to be much more cache efficient. Just a almost random thought. -- Andre
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