Re: still getting allocation failures (was Re: [PATCH] vmscan: Stop kswapd waiting on congestion when the min watermark is not being met V2)

Corrado Zoccolo
2009-12-14T08:49:39Z

Hi Tobi,
On Mon, Dec 14, 2009 at 6:59 AM, Tobias Oetiker <tobi@oetiker.ch> wrote:
> Hi Corrado,
>
> Dec 3 Corrado Zoccolo wrote:
>
>> Hi Tobias,
>> does the patch in http://lkml.org/lkml/2009/11/30/301 help with your
>> high order allocation problems?
>> It seems that you have lot of memory, but high order pages do not show up.
>> The patch should make them more likely to appear.
>> On my machine (that has much less ram than yours), with the patch, I
>> always have order-10 pages available.
>
> I have tried it and ... it does not work, the  page allocation
> failure still shows. BUT while testing it on two machines I found that it
> only shows on on machine. The workload on the two machines is
> similar (they both run virtualbox) and also the available memory.

Where those both failing before the patch?
Did the order of failure change?

> Could it be caused by a hardware driver ?
It should be something that is taking more time to release pages, but
I don't know what can it be. What happens if you drop the caches when
you are getting failures? Does the failure rate drops as if you had
just rebooted?
Can you log at regular intervals the content of /proc/buddyinfo, and
try correlating when the number of pages of the requested order are
becoming scarce with some other event?

Thanks,
Corrado
>
> cheers
> tobi
>
> --
> Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland
> http://it.oetiker.ch tobi@oetiker.ch ++41 62 775 9902 / sb: -9900
>

--
__________________________________________________________________________

dott. Corrado Zoccolo mailto:czoccolo@gmail.com
PhD - Department of Computer Science - University of Pisa, Italy
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