Hillo Mel On Tue, Sep 10, 2013 at 5:32 PM, Mel Gorman <mgorman@xxxxxxx> 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 <mgorman@xxxxxxx> > --- [...] > @@ -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? > - /* > * Rate-limit the amount of data that is being migrated to a node. > * Optimal placement is no good if the memory bus is saturated and > * all the time is being spent migrating! -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>