On Wed, Nov 23, 2011 at 9:45 PM, Mel Gorman <mgorman@xxxxxxx> wrote: > On Wed, Nov 23, 2011 at 09:05:08PM +0800, Nai Xia wrote: >> > <SNIP> >> > >> > Where are you adding this check? >> > >> > If you mean in __unmap_and_move(), the check is unnecessary unless >> > another subsystem starts using sync-light compaction. With this series, >> > only direct compaction cares about MIGRATE_SYNC_LIGHT. If the page is >> >> But I am still a little bit confused that if MIGRATE_SYNC_LIGHT is only >> used by direct compaction and another mode can be used by it: >> MIGRATE_ASYNC also does not write dirty pages, then why not also >> do an (current->flags & PF_MEMALLOC) test before writing out pages, > > Why would it be necessary? > Why would it be better than what is there now? I mean, if MIGRATE_SYNC_LIGHT --> (current->flags & PF_MEMALLOC), and MIGRATE_SYNC_LIGHT --> no dirty writeback, and (current->flags & PF_MEMALLOC) ---> (MIGRATE_SYNC_LIGHT || MIGRATE_ASYNC) and MIGRATE_ASYNC --> no dirty writeback, then why not simply (current->flags & PF_MEMALLOC) ---> no dirty writeback and keep the sync meaning as it was? Hoping I get myself clear this time...... > >> like we already did for the page lock condition, but adding a new mode >> instead? >> > > I'm afraid I am missing the significance of your question or how it > might apply to the problem at hand. Sorry, It always takes some effort for me to get myself understood when expressing a complicated thing. That's always my fault ;) Thanks, Nai > > -- > Mel Gorman > SUSE Labs > -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href