Messages in this thread | | | Date | Fri, 30 Sep 2011 23:43:41 +0200 | From | Johannes Weiner <> | Subject | Re: [PATCH -v2 -mm] add extra free kbytes tunable |
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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@redhat.com>
Acked-by: Johannes Weiner <jweiner@redhat.com>
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.
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