Date: Wed, 21 Dec 2016 11:32:09 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r310363 - stable/10/sys/vm Message-ID: <201612211132.uBLBW9Ud019011@repo.freebsd.org>
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Author: kib Date: Wed Dec 21 11:32:08 2016 New Revision: 310363 URL: https://svnweb.freebsd.org/changeset/base/310363 Log: MFC r310098: Provide introductory description of the default pager. Modified: stable/10/sys/vm/default_pager.c Directory Properties: stable/10/ (props changed) Modified: stable/10/sys/vm/default_pager.c ============================================================================== --- stable/10/sys/vm/default_pager.c Wed Dec 21 09:59:55 2016 (r310362) +++ stable/10/sys/vm/default_pager.c Wed Dec 21 11:32:08 2016 (r310363) @@ -63,6 +63,16 @@ static boolean_t default_pager_haspage(v int *); /* * pagerops for OBJT_DEFAULT - "default pager". + * + * This pager handles anonymous (no handle) swap-backed memory, just + * like the swap pager. It allows several optimizations based on the + * fact that no pages of a default object can be swapped out. The + * most important optimization is in vm_fault(), where the pager is + * never asked for a non-resident page. Instead, a freshly allocated + * zeroed page is used. + * + * On the first request to page out a page from a default object, the + * object is converted to swap pager type. */ struct pagerops defaultpagerops = { .pgo_alloc = default_pager_alloc,
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