On Mon, Mar 05, 2012 at 02:30:29PM -0800, Fengguang Wu wrote: > On Mon, Mar 05, 2012 at 04:11:15PM -0500, Vivek Goyal wrote: ... > > But looks like we don't much choice. As buffered writes can be controlled > > at two levels, we probably need two knobs. Also controlling writes while > > entring cache limits will be global and not per device (unlinke currnet > > per device limit in blkio controller). Having separate control for "dirty > > rate limit" leaves the scope for implementing write control at device > > level in the future (As some people prefer that). In possibly two > > solutions can co-exist in future. > > Good point. balance_dirty_pages() has no idea about the devices at > all. So the rate limit for buffered writes can hardly be unified with > the per-device rate limit for direct writes. > I think balance_dirty_pages() can have an idea about devices. We can get a reference to the right block device / request queue from the address_space: bdev = mapping->host->i_sb->s_bdev; q = bdev_get_queue(bdev); (NULL pointer dereferences apart). -Andrea -- 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=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>