On Tue, 2014-05-06 at 03:42 +0000, Alan Cox wrote: > Author: alc > Date: Tue May 6 03:42:04 2014 > New Revision: 265418 > URL: http://svnweb.freebsd.org/changeset/base/265418 > > Log: > 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. > > Reported by: avg > MFC after: 1 week > Sponsored by: EMC / Isilon Storage Division > > Modified: > head/sys/vm/vm_pageout.c > > Modified: head/sys/vm/vm_pageout.c > ============================================================================== > --- head/sys/vm/vm_pageout.c Tue May 6 03:38:04 2014 (r265417) > +++ head/sys/vm/vm_pageout.c Tue May 6 03:42:04 2014 (r265418) > @@ -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. >
Does this address the observation that several folks have made on current@ that pages are being pushed to swap much more agressively than in the past, even when the system doesn't seem short of memory? -- Ian _______________________________________________ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
