On Wed, Apr 10, 2013 at 11:56:08AM +0100, Mel Gorman wrote: > During major activity there is likely to be "good" behaviour > with stalls roughly every 30 seconds roughly corresponding to > dirty_expire_centiseconds. As you'd expect, the flusher thread is stuck > when this happens. > > 237 ? 00:00:00 flush-8:0 > [<ffffffff811a35b9>] sleep_on_buffer+0x9/0x10 > [<ffffffff811a35ee>] __lock_buffer+0x2e/0x30 > [<ffffffff8123a21f>] do_get_write_access+0x43f/0x4b0 If we're stalling on lock_buffer(), that implies that buffer was being written, and for some reason it was taking a very long time to complete. It might be worthwhile to put a timestamp in struct dm_crypt_io, and record the time when a particular I/O encryption/decryption is getting queued to the kcryptd workqueues, and when they finally squirt out. Something else that might be worth trying is to add WQ_HIGHPRI to the workqueue flags and see if that makes a difference. - Ted -- 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>