Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 69b62d01 authored by Jens Axboe's avatar Jens Axboe
Browse files

writeback: disable periodic old data writeback for !dirty_writeback_centisecs 



Prior to 2.6.32, setting /proc/sys/vm/dirty_writeback_centisecs disabled
periodic dirty writeback from kupdate. This got broken and now causes
excessive sys CPU usage if set to zero, as we'll keep beating on
schedule().

Cc: stable@kernel.org
Reported-by: default avatarJustin Maggard <jmaggard10@gmail.com>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 2395e463

fs/fs-writeback.c

+12 −2
Original line number Diff line number Diff line
@@ -852,6 +852,12 @@ static long wb_check_old_data_flush(struct bdi_writeback *wb) 
	unsigned long expired;

	long nr_pages;



	/*

	 * When set to zero, disable periodic writeback

	 */

	if (!dirty_writeback_interval)

		return 0;



	expired = wb->last_old_flush +

			msecs_to_jiffies(dirty_writeback_interval * 10);

	if (time_before(jiffies, expired))
@@ -947,8 +953,12 @@ int bdi_writeback_task(struct bdi_writeback *wb) 
				break;

		}



		if (dirty_writeback_interval) {

			wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10);

			schedule_timeout_interruptible(wait_jiffies);

		} else

			schedule();



		try_to_freeze();

	}