Re: size of swapped-out part of the process

["Victoria Muntean" <vikimun@gmail.com>]

On Mon, Nov 17, 2008 at 4:02 PM, Hugh Dickins <hugh@veritas.com> wrote:
> On Mon, 17 Nov 2008, Victoria Muntean wrote:
>> How can I calculate size of swapped-out part of the process from
>> /proc/PID/*, even if approximately ?
>> For example, I have VmSize=1216192 kB, VmRSS = 628788 kB, but global
>> swap-in-use==0.
>> Hence (VmSize - VmRSS) is far from being swapped-out part of the
>> process. What is ?
>
> I'm sorry, we don't record those numbers per process or per mm,
> so you won't find them in /proc/PID/status or /proc/PID/statm.
>
> And we'd probably resist accepting a patch to add them,
> so as not to enlarge key data structures to hold them.
>
> There's also an ambiguity about what "swapped-out" means: does
> it include shared file pages which were once mapped into the
> process, but have since been freed under memory pressure?
>
> But it looks like you're interested in swapped-out to mean written
> on swap.  In that case, if you have CONFIG_PROC_PAGE_MONITOR=y,
> you can read /proc/PID/smaps and add up all the "Swap:" lines.

ok thanks

> But don't keep reading it in a tight loop: that would
> tend to detract from the performance of your system.