Date: Fri, 30 Dec 2016 18:30:24 +0100
From: Michal Hocko <mhocko@kernel.org>
To: Minchan Kim <minchan@kernel.org>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>, linux-mm@kvack.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Mel Gorman <mgorman@suse.de>, Johannes Weiner <hannes@cmpxchg.org>,
        Vlastimil Babka <vbabka@suse.cz>, Rik van Riel <riel@redhat.com>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/7] mm, vmscan: add active list aging tracepoint
Message-ID: <20161230173023.GA4962@dhcp22.suse.cz>
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 <20161228153032.10821-3-mhocko@kernel.org>
 <20161229053359.GA1815@bbox>
 <20161229075243.GA29208@dhcp22.suse.cz>
 <20161230014853.GA4184@bbox>
 <20161230092636.GA13301@dhcp22.suse.cz>
 <20161230160456.GA7267@bbox>
 <20161230163742.GK13301@dhcp22.suse.cz>
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On Fri 30-12-16 17:37:42, Michal Hocko wrote:
> On Sat 31-12-16 01:04:56, Minchan Kim wrote:
[...]
> > > 	- nr_rotated pages which tells us that we are hitting referenced
> > > 	  pages which are deactivated. If this is a large part of the
> > > 	  reported nr_deactivated pages then the active list is too small
> > 
> > It might be but not exactly. If your goal is to know LRU size, it can be
> > done in get_scan_count. I tend to agree LRU size is helpful for
> > performance analysis because decreased LRU size signals memory shortage
> > then performance drop.
> 
> No, I am not really interested in the exact size but rather to allow to
> find whether we are aging the active list too early...

But thinking about that some more, maybe sticking with the nr_rotated
terminology is rather confusing and displaying the value as nr_referenced
would be more clear.
-- 
Michal Hocko
SUSE Labs