On Thu, Sep 01, 2011 at 03:26:50PM -0400, Rik van Riel wrote: > Add a userspace visible knob to tell the VM to keep an extra amount > of memory free, by increasing the gap between each zone's min and > low watermarks. > > This is useful for realtime applications that call system > calls and have a bound on the number of allocations that happen > in any short time period. In this application, extra_free_kbytes > would be left at an amount equal to or larger than than the > maximum number of allocations that happen in any burst. > > It may also be useful to reduce the memory use of virtual > machines (temporarily?), in a way that does not cause memory > fragmentation like ballooning does. > > Signed-off-by: Rik van Riel<riel@xxxxxxxxxx> Acked-by: Johannes Weiner <jweiner@xxxxxxxxxx> Btw, I wonder if there should be a waking of the kswapds in setup_per_zone_wmarks() in general to make sure the new watermarks are met. But that applies to min_free_kbytes as well, so not a requirement for this patch. -- 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>