> - use tagging also for WB_SYNC_NONE writeback - there's problem with an > interaction with wbc->nr_to_write. If we tag all dirty pages, we can > spend too much time tagging when we write only a few pages in the end > because of nr_to_write. If we tag only say nr_to_write pages, we may > not have enough pages tagged because some pages are written out by > someone else and so we would have to restart and tagging would become This could be addressed by ignoring nr_to_write for the WB_SYNC_NONE writeback triggered by sync(). write_cache_pages() already ignored nr_to_write for WB_SYNC_ALL. > essentially useless. So my option is - switch to tagging for WB_SYNC_NONE > writeback if we can get rid of nr_to_write. But that's a story for > a different patch set. Besides introducing overheads, it will be a policy change in which the system loses control to somehow "throttle" writeback of huge files. So it may be safer to enlarge nr_to_write instead of canceling it totally. Thanks, Fengguang -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>