Date: Tue, 13 May 2014 05:26:43 +0000 (UTC) From: Alan Cox <alc@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: r265945 - stable/10/sys/vm Message-ID: <201405130526.s4D5Qh5f075845@svn.freebsd.org>
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Author: alc Date: Tue May 13 05:26:43 2014 New Revision: 265945 URL: http://svnweb.freebsd.org/changeset/base/265945 Log: MFC r265418 Prior to r254304, a separate function, vm_pageout_page_stats(), was used to periodically update the reference status of the active pages. This function was called, instead of vm_pageout_scan(), when memory was not scarce. The objective was to provide up to date reference status for active pages in case memory did become scarce and active pages needed to be deactivated. The active page queue scan performed by vm_pageout_page_stats() was virtually identical to that performed by vm_pageout_scan(), and so r254304 eliminated vm_pageout_page_stats(). Instead, vm_pageout_scan() is called with the parameter "pass" set to zero. The intention was that when pass is zero, vm_pageout_scan() would only scan the active queue. However, the variable page_shortage can still be greater than zero when memory is not scarce and vm_pageout_scan() is called with pass equal to zero. Consequently, the inactive queue may be scanned and dirty pages laundered even though that was not intended by r254304. This revision fixes that. Modified: stable/10/sys/vm/vm_pageout.c Directory Properties: stable/10/ (props changed) Modified: stable/10/sys/vm/vm_pageout.c ============================================================================== --- stable/10/sys/vm/vm_pageout.c Tue May 13 05:21:54 2014 (r265944) +++ stable/10/sys/vm/vm_pageout.c Tue May 13 05:26:43 2014 (r265945) @@ -942,13 +942,15 @@ vm_pageout_scan(struct vm_domain *vmd, i */ addl_page_shortage = 0; - deficit = atomic_readandclear_int(&vm_pageout_deficit); - /* * Calculate the number of pages we want to either free or move * to the cache. */ - page_shortage = vm_paging_target() + deficit; + if (pass > 0) { + deficit = atomic_readandclear_int(&vm_pageout_deficit); + page_shortage = vm_paging_target() + deficit; + } else + page_shortage = deficit = 0; /* * maxlaunder limits the number of dirty pages we flush per scan.
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