On Thu, Sep 12, 2013 at 10:10:13AM +0800, Hillf Danton wrote: > Hillo Mel > > On Tue, Sep 10, 2013 at 5:32 PM, Mel Gorman <[email protected]> wrote: > > Currently automatic NUMA balancing is unable to distinguish between false > > shared versus private pages except by ignoring pages with an elevated > > page_mapcount entirely. This avoids shared pages bouncing between the > > nodes whose task is using them but that is ignored quite a lot of data. > > > > This patch kicks away the training wheels in preparation for adding support > > for identifying shared/private pages is now in place. The ordering is so > > that the impact of the shared/private detection can be easily measured. Note > > that the patch does not migrate shared, file-backed within vmas marked > > VM_EXEC as these are generally shared library pages. Migrating such pages > > is not beneficial as there is an expectation they are read-shared between > > caches and iTLB and iCache pressure is generally low. > > > > Signed-off-by: Mel Gorman <[email protected]> > > --- > [...] > > @@ -1658,13 +1660,6 @@ int migrate_misplaced_transhuge_page(struct > > mm_struct *mm, > > int page_lru = page_is_file_cache(page); > > > > /* > > - * Don't migrate pages that are mapped in multiple processes. > > - * TODO: Handle false sharing detection instead of this hammer > > - */ > > - if (page_mapcount(page) != 1) > > - goto out_dropref; > > - > Is there rmap walk when migrating THP? >
Should not be necessary for THP. -- Mel Gorman SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
