Messages in this thread | | | From | Satoru Moriya <> | Date | Tue, 11 Oct 2011 15:32:11 -0400 | Subject | RE: [PATCH -v2 -mm] add extra free kbytes tunable |
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On 10/10/2011 06:37 PM, Andrew Morton wrote: > On Fri, 7 Oct 2011 20:08:19 -0700 (PDT) David Rientjes > <rientjes@google.com> wrote: > >> On Thu, 1 Sep 2011, Rik van Riel wrote: > > The page allocator already tries harder if the caller has > rt_task(current). Why is this inadequate? Can we extend this idea > further to fix whatever-the-problem-is?
Actually page allocator decreases min watermark to 3/4 * min watermark for rt-task. But in our case some applications create a lot of processes and if all of them are rt-task, the amount of watermark bonus(1/4 * min watermark) is not enough.
If we can tune the amount of bonus, it may be fine. But that is almost all same as extra free kbytes.
> Does there exist anything like a test case which demonstrates the need > for this feature?
Unfortunately I don't have a real test case but just simple one. And in my simple test case, I can avoid direct reclaim if we set workload as rt-task.
The simple test case I used is following: http://marc.info/?l=linux-mm&m=131605773321672&w=2
Regards, Satoru
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