linux-kernel - Re: [PATCH] mm: show stats for non-default hugepage sizes in /proc/meminfo

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Message-ID: <2579a26d-81d1-732e-ef57-33bb4c293cd6@oracle.com>
Date:   Mon, 13 Nov 2017 10:30:10 -0800
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     Dave Hansen <dave.hansen@...el.com>, Roman Gushchin <guro@...com>
Cc:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Johannes Weiner <hannes@...xchg.org>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Andrea Arcangeli <aarcange@...hat.com>, kernel-team@...com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: show stats for non-default hugepage sizes in
 /proc/meminfo

On 11/13/2017 10:17 AM, Dave Hansen wrote:
> On 11/13/2017 10:11 AM, Roman Gushchin wrote:
>> On Mon, Nov 13, 2017 at 09:06:32AM -0800, Dave Hansen wrote:
>>> On 11/13/2017 08:03 AM, Roman Gushchin wrote:
>>>> To solve this problem, let's display stats for all hugepage sizes.
>>>> To provide the backward compatibility let's save the existing format
>>>> for the default size, and add a prefix (e.g. 1G_) for non-default sizes.
>>>
>>> Is there something keeping you from using the sysfs version of this
>>> information?
>>
>> Just answered the same question to Michal.
>>
>> In two words: it would be nice to have a high-level overview of
>> memory usage in the system in /proc/meminfo. 
> 
> I don't think it's worth cluttering up meminfo for this, imnho.

I tend to agree that it would be better not to add additional huge page
sizes here.  It may not seem too intrusive to (potentially) add one extra
set of entries for GB huge pages on x86.  However, other architectures
such as powerpc or sparc have several several huge pages sizes that could
potentially be added here as well.  Although, in practice one does tend
to use a single huge pages size.  If you change the default huge page
size, then those entries will be in /proc/meminfo.

-- 
Mike Kravetz