SuperPages utilization survey
Mikolaj Golub
trociny at freebsd.org
Sat Jun 9 09:03:49 UTC 2012
On Sat, 9 Jun 2012 11:38:22 +0300 Konstantin Belousov wrote:
KB> On Sat, Jun 09, 2012 at 10:31:17AM +0300, Mikolaj Golub wrote:
>>
>> On Fri, 1 Jun 2012 14:54:48 +0200 Ivan Voras wrote:
>>
>> IV> On 1 June 2012 14:35, Wojciech Puchar <wojtek at wojtek.tensor.gdynia.pl> wrote:
>> >>> http://people.freebsd.org/~ivoras/stuff/spsurvey.py
>>
>> ...
>>
>> IV> If anyone posts more data, I'll analyse it. I'm more worried about the
>> IV> granularity of procstat, where it marks the entire region if a single
>> IV> superpage exists in it - it means any such analysis is only
>> IV> approximate.
>>
>> Here is a patch (for kernel and procstat) that allows to see amount of pages
>> mapped to superpages.
>>
>> http://people.freebsd.org/~trociny/procstat-superpages.cnt.1.patch
>>
>> Not sure it is useful enough to be committed.
KB> Superpage aggregates mappings for several normal-sized pages.
KB> As a consequence, when you iterate over small pages in
KB> sysctl_kern_proc_vmmap(), you account each superpage as many time as
KB> much constituent small pages it contains.
This is exactly what my intention was to count: how much memory are handled by
superpages (using normal-sized page as a measurement unit), not amount of
superpages. And I think this is what Ivan wanted to know. Do you think it is
better to return number of superpages?
--
Mikolaj Golub
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