linux-kernel - Re: [PATCH] smaps: fill missing fields for vma(VM

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Message-ID: <alpine.DEB.2.10.1508051917430.4843@chino.kir.corp.google.com>
Date:	Wed, 5 Aug 2015 19:18:44 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Jörn Engel <joern@...estorage.com>
cc:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Mike Kravetz <mike.kravetz@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] smaps: fill missing fields for vma(VM_HUGETLB)

On Tue, 4 Aug 2015, Jörn Engel wrote:

> > From: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
> > Subject: [PATCH] smaps: fill missing fields for vma(VM_HUGETLB)
> > 
> > Currently smaps reports many zero fields for vma(VM_HUGETLB), which is
> > inconvenient when we want to know per-task or per-vma base hugetlb usage.
> > This patch enables these fields by introducing smaps_hugetlb_range().
> > 
> > before patch:
> > 
> >   Size:              20480 kB
> >   Rss:                   0 kB
> >   Pss:                   0 kB
> >   Shared_Clean:          0 kB
> >   Shared_Dirty:          0 kB
> >   Private_Clean:         0 kB
> >   Private_Dirty:         0 kB
> >   Referenced:            0 kB
> >   Anonymous:             0 kB
> >   AnonHugePages:         0 kB
> >   Swap:                  0 kB
> >   KernelPageSize:     2048 kB
> >   MMUPageSize:        2048 kB
> >   Locked:                0 kB
> >   VmFlags: rd wr mr mw me de ht
> > 
> > after patch:
> > 
> >   Size:              20480 kB
> >   Rss:               18432 kB
> >   Pss:               18432 kB
> >   Shared_Clean:          0 kB
> >   Shared_Dirty:          0 kB
> >   Private_Clean:         0 kB
> >   Private_Dirty:     18432 kB
> >   Referenced:        18432 kB
> >   Anonymous:         18432 kB
> >   AnonHugePages:         0 kB
> >   Swap:                  0 kB
> >   KernelPageSize:     2048 kB
> >   MMUPageSize:        2048 kB
> >   Locked:                0 kB
> >   VmFlags: rd wr mr mw me de ht
> 
> Nice!
> 

Hmm, wouldn't this be confusing since VmRSS in /proc/pid/status doesn't 
match the rss shown in smaps, since hugetlb mappings aren't accounted in 
get_mm_rss()?

Not sure this is a good idea, I think consistency amongst rss values would 
be more important.