On Thu, 2009-09-24 at 16:33 +0800, Wu Fengguang wrote: > Yeah, FIFO queuing should be good enough. > > I'd like to propose one more data structure for evaluation :) > > - bdi->throttle_lock > - bdi->throttle_list pages to sync for each waiting task, taken from sync_writeback_pages() > - bdi->throttle_pages (counted down) pages to sync for the head task, shall be atomic_t > > In balance_dirty_pages(), it would do > > nr_to_sync = sync_writeback_pages() > if (list_empty(bdi->throttle_list)) # I'm the only task > bdi->throttle_pages = nr_to_sync > append nr_to_sync to bdi->throttle_list > kick off background writeback > wait > remove itself from bdi->throttle_list and wait list > set bdi->throttle_pages for new head task (or LONG_MAX) > > In __bdi_writeout_inc(), it would do > > if (--bdi->throttle_pages <= 0) > check and wake up head task > > In wb_writeback(), it would do > > if (args->for_background && exiting) > wake up all throttled tasks > > To prevent wake up too many tasks at the same time, it can relax the > background threshold a bit, so that __bdi_writeout_inc() become the > only wake up point in normal cases. > > if (args->for_background && !list_empty(bdi->throttle_list) && > over background_thresh - background_thresh / 32) > keep write pages; Right, something like that ought to work well, or at least sounds like worth a try ;-) -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
