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From: Johannes Weiner <hannes@cmpxchg.org>
To: Vladimir Davydov <vdavydov@parallels.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@kernel.org>,
	Minchan Kim <minchan@kernel.org>, Rik van Riel <riel@redhat.com>,
	Mel Gorman <mgorman@suse.de>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] mm: make workingset detection logic memcg aware
Date: Mon, 3 Aug 2015 09:23:58 -0400	[thread overview]
Message-ID: <20150803132358.GA18399@cmpxchg.org> (raw)
In-Reply-To: <9662034e14549b9e1445684f674063ce8b092cb0.1438599199.git.vdavydov@parallels.com>

On Mon, Aug 03, 2015 at 03:04:22PM +0300, Vladimir Davydov wrote:
> @@ -179,8 +180,9 @@ static void unpack_shadow(void *shadow,
>  	eviction = entry;
>  
>  	*zone = NODE_DATA(nid)->node_zones + zid;
> +	*lruvec = mem_cgroup_page_lruvec(page, *zone);
>  
> -	refault = atomic_long_read(&(*zone)->inactive_age);
> +	refault = atomic_long_read(&(*lruvec)->inactive_age);
>  	mask = ~0UL >> (NODES_SHIFT + ZONES_SHIFT +
>  			RADIX_TREE_EXCEPTIONAL_SHIFT);
>  	/*

You can not compare an eviction shadow entry from one lruvec with the
inactive age of another lruvec. The inactive ages are not related and
might differ significantly: memcgs are created ad hoc, memory hotplug,
page allocator fairness drift. In those cases the result will be pure
noise.

As much as I would like to see a simpler way, I am pessimistic that
there is a way around storing memcg ids in the shadow entries.

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  reply	other threads:[~2015-08-03 13:24 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-08-03 12:04 [PATCH 0/3] Make " Vladimir Davydov
2015-08-03 12:04 ` [PATCH 1/3] mm: move workingset_activation under lru_lock Vladimir Davydov
2015-08-03 12:04 ` [PATCH 2/3] mm: make workingset detection logic memcg aware Vladimir Davydov
2015-08-03 13:23   ` Johannes Weiner [this message]
2015-08-03 13:52     ` Vladimir Davydov
2015-08-03 20:55       ` Johannes Weiner
2015-08-04  8:13         ` Vladimir Davydov
2015-08-03 12:04 ` [PATCH 3/3] mm: workingset: make shadow node shrinker " Vladimir Davydov
2015-08-05  1:34 ` [PATCH 0/3] Make workingset detection logic " Kamezawa Hiroyuki
2015-08-06  8:59   ` Vladimir Davydov
2015-08-07  1:38     ` Kamezawa Hiroyuki
2015-08-08 13:05       ` Vladimir Davydov
2015-08-09 14:12         ` Kamezawa Hiroyuki
2015-08-10  8:14           ` Vladimir Davydov
2015-08-11 15:59             ` Kamezawa Hiroyuki

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