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From: Michal Hocko <mhocko@kernel.org>
To: Sandipan Das <sandipan@linux.ibm.com>
Cc: akpm@linux-foundation.org, linux-mm@kvack.org,
	khlebnikov@yandex-team.ru, kirill@shutemov.name,
	aneesh.kumar@linux.ibm.com, srikar@linux.vnet.ibm.com
Subject: Re: [PATCH] mm: vmstat: Use zeroed stats for unpopulated zones
Date: Mon, 4 May 2020 12:26:31 +0200	[thread overview]
Message-ID: <20200504102441.GM22838@dhcp22.suse.cz> (raw)
In-Reply-To: <20200504070304.127361-1-sandipan@linux.ibm.com>

On Mon 04-05-20 12:33:04, Sandipan Das wrote:
> For unpopulated zones, the pagesets point to the common
> boot_pageset which can have non-zero vm_numa_stat counts.
> Because of this memory-less nodes end up having non-zero
> NUMA statistics. This can be observed on any architecture
> that supports memory-less NUMA nodes.
> 
> E.g.
> 
>   $ numactl -H
>   available: 2 nodes (0-1)
>   node 0 cpus: 0 1 2 3
>   node 0 size: 0 MB
>   node 0 free: 0 MB
>   node 1 cpus: 4 5 6 7
>   node 1 size: 8131 MB
>   node 1 free: 6980 MB
>   node distances:
>   node   0   1
>     0:  10  40
>     1:  40  10
> 
>   $ numastat
>                              node0           node1
>   numa_hit                     108           56495
>   numa_miss                      0               0
>   numa_foreign                   0               0
>   interleave_hit                 0            4537
>   local_node                   108           31547
>   other_node                     0           24948
> 
> Hence, return zero explicitly for all the stats of an
> unpopulated zone.

I hope I am not just confused but I would expect that at least
numa_foreign and other_node to be non zero.

-- 
Michal Hocko
SUSE Labs


  reply	other threads:[~2020-05-04 10:26 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-04  7:03 [PATCH] mm: vmstat: Use zeroed stats for unpopulated zones Sandipan Das
2020-05-04 10:26 ` Michal Hocko [this message]
2020-05-06 13:33   ` Vlastimil Babka
2020-05-06 14:02     ` Michal Hocko
2020-05-06 15:09       ` Vlastimil Babka
2020-05-06 15:24         ` Michal Hocko
2020-05-06 15:50           ` Vlastimil Babka
2020-05-07  7:09             ` Michal Hocko
2020-05-07  9:05               ` Sandipan Das
2020-05-07  9:08                 ` Sandipan Das
2020-05-07 11:07                   ` Vlastimil Babka
2020-05-07 11:17                     ` Sandipan Das

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