Date: Thu, 16 Jul 2015 13:02:11 +0300
From: Vladimir Davydov <vdavydov@parallels.com>
To: Andres Lagar-Cavilla <andreslc@google.com>
CC: Andrew Morton <akpm@linux-foundation.org>,
        Minchan Kim <minchan@kernel.org>,
        Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
        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 -mm v8 0/7] idle memory tracking
Message-ID: <20150716100211.GC2001@esperanza>
References: <cover.1436967694.git.vdavydov@parallels.com>
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On Wed, Jul 15, 2015 at 01:47:15PM -0700, Andres Lagar-Cavilla wrote:
> I think the remaining question here is performance.
> 
> Have you conducted any studies where
> - there is a workload
> - a daemon is poking kpageidle every N seconds/minutes
> - what is the daemon cpu consumption?
> - what is the workload degradation if any?
> 
> N candidates include 30 seconds, 1 minute, 2 minutes, 5 minutes....
> 
> Workload candidates include TPC, spec int memory intensive things like
> 429.mcf, stream (http://www.cs.virginia.edu/stream/ "sustainable
> memory bandwidth" vs floating point performance)
> 
> I'm not asking for a research paper, but if, say, a 2 minute-period
> daemon introduces no degradation and adds up to a minute of cpu per
> hour, then we're golden.

Fair enough. Will do that soon and report back.

Thanks a lot for the review, it was really helpful!

Vladimir
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