Re: [PATCH v2 1/1] mm: smaps: split PSS into components

[Michal Hocko <mhocko@kernel.org>]

On Fri 31-05-19 08:04:01, Michal Hocko wrote:
> [Please always Cc linux-api mailing list (now added) when adding a new
> user visible API. Keeping the rest of the email intact for reference]
> 
> On Thu 30-05-19 17:26:33, semenzato@chromium.org wrote:
> > From: Luigi Semenzato <semenzato@chromium.org>
> > 
> > Report separate components (anon, file, and shmem)
> > for PSS in smaps_rollup.
> > 
> > This helps understand and tune the memory manager behavior
> > in consumer devices, particularly mobile devices.  Many of
> > them (e.g. chromebooks and Android-based devices) use zram
> > for anon memory, and perform disk reads for discarded file
> > pages.  The difference in latency is large (e.g. reading
> > a single page from SSD is 30 times slower than decompressing
> > a zram page on one popular device), thus it is useful to know
> > how much of the PSS is anon vs. file.

Could you describe how exactly are those new counters going to be used?

I do not expect this to add a visible penalty to users who are not going
to use the counter but have you tried to measure that?

-- 
Michal Hocko
SUSE Labs