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Date: Thu, 14 May 2015 13:17:35 +0200
From: Vlastimil Babka <vbabka@suse.cz>
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To: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>, linux-mm@kvack.org,
        Jerome Marchand <jmarchan@redhat.com>
CC: linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>,
        linux-doc@vger.kernel.org, Hugh Dickins <hughd@google.com>,
        Michal Hocko <mhocko@suse.cz>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Cyrill Gorcunov <gorcunov@openvz.org>,
        Randy Dunlap <rdunlap@infradead.org>, linux-s390@vger.kernel.org,
        Martin Schwidefsky <schwidefsky@de.ibm.com>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Paul Mackerras <paulus@samba.org>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Oleg Nesterov <oleg@redhat.com>, Linux API <linux-api@vger.kernel.org>
Subject: Re: [PATCH v2 3/4] mm, shmem: Add shmem resident memory accounting
References: <1427474441-17708-1-git-send-email-vbabka@suse.cz> <1427474441-17708-4-git-send-email-vbabka@suse.cz> <55158EB5.5040301@yandex-team.ru>
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On 03/27/2015 06:09 PM, Konstantin Khlebnikov wrote:
> On 27.03.2015 19:40, Vlastimil Babka wrote:
>> From: Jerome Marchand <jmarchan@redhat.com>
>>
>> Currently looking at /proc/<pid>/status or statm, there is no way to
>> distinguish shmem pages from pages mapped to a regular file (shmem
>> pages are mapped to /dev/zero), even though their implication in
>> actual memory use is quite different.
>> This patch adds MM_SHMEMPAGES counter to mm_rss_stat to account for
>> shmem pages instead of MM_FILEPAGES.
>>
>> Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
>> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
>> ---
>
>
>> --- a/include/linux/mm_types.h
>> +++ b/include/linux/mm_types.h
>> @@ -327,9 +327,12 @@ struct core_state {
>>    };
>>
>>    enum {
>> -	MM_FILEPAGES,
>> -	MM_ANONPAGES,
>> -	MM_SWAPENTS,
>> +	MM_FILEPAGES,	/* Resident file mapping pages */
>> +	MM_ANONPAGES,	/* Resident anonymous pages */
>> +	MM_SWAPENTS,	/* Anonymous swap entries */
>> +#ifdef CONFIG_SHMEM
>> +	MM_SHMEMPAGES,	/* Resident shared memory pages */
>> +#endif
>
> I prefer to keep that counter unconditionally:
> kernel has MM_SWAPENTS even without CONFIG_SWAP.

Hmm, so just for consistency? I don't see much reason to make life 
harder for tiny systems, especially when it's not too much effort.

>
>>    	NR_MM_COUNTERS
>>    };
>>
>
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