On Thu, Aug 11, 2011 at 01:10:26AM +0800, Peter Zijlstra wrote: > On Wed, 2011-08-10 at 22:00 +0800, Wu Fengguang wrote: > > > > > Although I'm not quite sure how he keeps fairness in light of the > > > sleep time bounding to MAX_PAUSE. > > > > Firstly, MAX_PAUSE will only be applied when the dirty pages rush > > high (dirty exceeded). Secondly, the dirty exceeded state is global > > to all tasks, in which case each task will sleep for MAX_PAUSE equally. > > So the fairness is still maintained in dirty exceeded state. > > Its not immediately apparent how dirty_exceeded and MAX_PAUSE interact, > but having everybody sleep MAX_PAUSE doesn't necessarily mean its fair, > its only fair if they dirty at the same rate. Yeah I forget to mention that, but when dirty_exceeded, the tasks will typically sleep for MAX_PAUSE on every 8 pages, so resulting in the same dirty rate :) Thanks, Fengguang -- 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>