Date: Wed, 29 Apr 2015 10:58:53 +0300
From: Vladimir Davydov <vdavydov@parallels.com>
To: Minchan Kim <minchan@kernel.org>
CC: Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>, Michal Hocko <mhocko@suse.cz>,
        Greg Thelen <gthelen@google.com>,
        Michel Lespinasse <walken@google.com>,
        David Rientjes <rientjes@google.com>,
        Pavel Emelyanov <xemul@parallels.com>,
        Cyrill Gorcunov <gorcunov@openvz.org>,
        Jonathan Corbet <corbet@lwn.net>, <linux-api@vger.kernel.org>,
        <linux-doc@vger.kernel.org>, <linux-mm@kvack.org>,
        <cgroups@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 0/3] idle memory tracking
Message-ID: <20150429075853.GC1694@esperanza>
References: <cover.1430217477.git.vdavydov@parallels.com>
 <20150429035722.GA11486@blaptop>
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Hi Minchan,

Thank you for taking a look at this patch set.

On Wed, Apr 29, 2015 at 12:57:22PM +0900, Minchan Kim wrote:
> On Tue, Apr 28, 2015 at 03:24:39PM +0300, Vladimir Davydov wrote:
> >  * /proc/kpageidle.  For each page this file contains a 64-bit number, which
> >    equals 1 if the page is idle or 0 otherwise, indexed by PFN. A page is
> 
> Why do we need 64bit per page to indicate just idle or not?

I don't think we need this, actually. I made this file 64 bit per page
only to conform to other /proc/kpage* files. Currently, I can't think of
any potential use for residual 63 bits, so personally I'm fine with 1
bit per page. If nobody comes with an idea about how > 1 bits could be
used, I'll switch /proc/kpageidle to a bitmask in the next iteration.

Thanks,
Vladimir
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