linux-kernel - Re: Re: Re: [RFC] autonuma: Support to scan page table asynchronously

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Message-ID: <20200417102129.23399-1-sjpark@amazon.com>
Date:   Fri, 17 Apr 2020 12:21:29 +0200
From:   SeongJae Park <sjpark@...zon.com>
To:     Peter Zijlstra <peterz@...radead.org>
CC:     SeongJae Park <sjpark@...zon.com>,
        "Huang, Ying" <ying.huang@...el.com>,
        Mel Gorman <mgorman@...hsingularity.net>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...hat.com>,
        Mel Gorman <mgorman@...e.de>, Rik van Riel <riel@...riel.com>,
        Daniel Jordan <daniel.m.jordan@...cle.com>,
        Tejun Heo <tj@...nel.org>, Dave Hansen <dave.hansen@...el.com>,
        Tim Chen <tim.c.chen@...el.com>,
        Aubrey Li <aubrey.li@...el.com>
Subject: Re: Re: Re: [RFC] autonuma: Support to scan page table asynchronously

On Fri, 17 Apr 2020 12:04:17 +0200 Peter Zijlstra <peterz@...radead.org> wrote:

> On Fri, Apr 17, 2020 at 09:05:08AM +0200, SeongJae Park wrote:
> > I think the main idea of DAMON[1] might be able to applied here.  Have you
> > considered it?
> > 
> > [1] https://lore.kernel.org/linux-mm/20200406130938.14066-1-sjpark@amazon.com/
> 
> I've ignored that entire thing after you said the information it
> provides was already available through the PMU.

Sorry if my answer made you confused.  What I wanted to say was that the
fundamental access checking mechanism that DAMON depends on is PTE Accessed bit
for now, but it could be modified to use PMU or other features instead.  In
other words, PMU on some architectures could provide the fundamental, low level
information for DAMON, as PTE Accessed bit does.  What DAMON does are efficient
control of the fundamental access checking features and making of elaborated
final informations, which PMU itself doesn't provide.


Thanks,
SeongJae Park