* [PATCH] Hugetlb pages rss accounting is incorrect in /proc/<pid>/smaps
@ 2017-10-24 23:56 Prakash Sangappa
2017-10-25 6:55 ` Michal Hocko
0 siblings, 1 reply; 3+ messages in thread
From: Prakash Sangappa @ 2017-10-24 23:56 UTC (permalink / raw)
To: linux-kernel, linux-mm
Cc: akpm, mhocko, minchan, rientjes, dancol, prakash.sangappa
Resident set size(Rss) accounting of hugetlb pages is not done
currently in /proc/<pid>/smaps. The pmap command reads rss from
this file and so it shows Rss to be 0 in pmap -x output for
hugetlb mapped vmas. This patch fixes it.
Signed-off-by: Prakash Sangappa <prakash.sangappa@oracle.com>
---
fs/proc/task_mmu.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 5589b4b..c7e1048 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -724,6 +724,7 @@ static int smaps_hugetlb_range(pte_t *pte, unsigned long hmask,
mss->shared_hugetlb += huge_page_size(hstate_vma(vma));
else
mss->private_hugetlb += huge_page_size(hstate_vma(vma));
+ mss->resident += huge_page_size(hstate_vma(vma));
}
return 0;
}
--
2.7.4
--
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] Hugetlb pages rss accounting is incorrect in /proc/<pid>/smaps
2017-10-24 23:56 [PATCH] Hugetlb pages rss accounting is incorrect in /proc/<pid>/smaps Prakash Sangappa
@ 2017-10-25 6:55 ` Michal Hocko
2017-10-25 22:45 ` Naoya Horiguchi
0 siblings, 1 reply; 3+ messages in thread
From: Michal Hocko @ 2017-10-25 6:55 UTC (permalink / raw)
To: Prakash Sangappa
Cc: linux-kernel, linux-mm, akpm, minchan, rientjes, dancol, Naoya Horiguchi
[CCing Naoya]
On Tue 24-10-17 16:56:08, Prakash Sangappa wrote:
> Resident set size(Rss) accounting of hugetlb pages is not done
> currently in /proc/<pid>/smaps. The pmap command reads rss from
> this file and so it shows Rss to be 0 in pmap -x output for
> hugetlb mapped vmas. This patch fixes it.
We do not account in rss because we do have a dedicated counters
depending on whether the hugetlb page is mapped privately or it is
shared. The reason this is not in RSS IIRC is that a large unexpected
RSS from hugetlb pages might confuse system monitors. This is one of
those backward compatibility issues when you start accounting something
too late.
> Signed-off-by: Prakash Sangappa <prakash.sangappa@oracle.com>
> ---
> fs/proc/task_mmu.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 5589b4b..c7e1048 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -724,6 +724,7 @@ static int smaps_hugetlb_range(pte_t *pte, unsigned long hmask,
> mss->shared_hugetlb += huge_page_size(hstate_vma(vma));
> else
> mss->private_hugetlb += huge_page_size(hstate_vma(vma));
> + mss->resident += huge_page_size(hstate_vma(vma));
> }
> return 0;
> }
> --
> 2.7.4
>
--
Michal Hocko
SUSE Labs
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] Hugetlb pages rss accounting is incorrect in /proc/<pid>/smaps
2017-10-25 6:55 ` Michal Hocko
@ 2017-10-25 22:45 ` Naoya Horiguchi
0 siblings, 0 replies; 3+ messages in thread
From: Naoya Horiguchi @ 2017-10-25 22:45 UTC (permalink / raw)
To: Michal Hocko
Cc: Prakash Sangappa, linux-kernel, linux-mm, akpm, minchan,
rientjes, dancol
On Wed, Oct 25, 2017 at 08:55:27AM +0200, Michal Hocko wrote:
> [CCing Naoya]
>
> On Tue 24-10-17 16:56:08, Prakash Sangappa wrote:
> > Resident set size(Rss) accounting of hugetlb pages is not done
> > currently in /proc/<pid>/smaps. The pmap command reads rss from
> > this file and so it shows Rss to be 0 in pmap -x output for
> > hugetlb mapped vmas. This patch fixes it.
>
> We do not account in rss because we do have a dedicated counters
> depending on whether the hugetlb page is mapped privately or it is
> shared. The reason this is not in RSS IIRC is that a large unexpected
> RSS from hugetlb pages might confuse system monitors.
Yes, that was the intention of separate counters for hugetlb.
> This is one of
> those backward compatibility issues when you start accounting something
> too late.
So new monitoring applications are supposed to check the new counters
to track hugetlb usages.
Thanks,
Naoya Horiguchi
>
> > Signed-off-by: Prakash Sangappa <prakash.sangappa@oracle.com>
> > ---
> > fs/proc/task_mmu.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> > index 5589b4b..c7e1048 100644
> > --- a/fs/proc/task_mmu.c
> > +++ b/fs/proc/task_mmu.c
> > @@ -724,6 +724,7 @@ static int smaps_hugetlb_range(pte_t *pte, unsigned long hmask,
> > mss->shared_hugetlb += huge_page_size(hstate_vma(vma));
> > else
> > mss->private_hugetlb += huge_page_size(hstate_vma(vma));
> > + mss->resident += huge_page_size(hstate_vma(vma));
> > }
> > return 0;
> > }
> > --
> > 2.7.4
> >
>
> --
> Michal Hocko
> SUSE Labs
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
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2017-10-24 23:56 [PATCH] Hugetlb pages rss accounting is incorrect in /proc/<pid>/smaps Prakash Sangappa
2017-10-25 6:55 ` Michal Hocko
2017-10-25 22:45 ` Naoya Horiguchi
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