SuperPages utilization survey

[Konstantin Belousov]

On Sat, Jun 09, 2012 at 12:03:43PM +0300, Mikolaj Golub wrote:
> 
> 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?
> 
Well, if I see a report informing me that some 2M region contains 512 super
pages, how should I interpret it ? For me, it is only one superpage (mapping)
that can be created in one 2M region.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 196 bytes
Desc: not available
Url : http://lists.freebsd.org/pipermail/freebsd-hackers/attachments/20120609/6adb3203/attachment.pgp