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From:   "Huang\, Ying" <ying.huang@intel.com>
To:     SeongJae Park <sj38.park@gmail.com>
Cc:     Mel Gorman <mgorman@suse.de>, SeongJae Park <sjpark@amazon.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        Peter Zijlstra <peterz@infradead.org>, <linux-mm@kvack.org>,
        <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@redhat.com>,
        Rik van Riel <riel@surriel.com>,
        Daniel Jordan <daniel.m.jordan@oracle.com>,
        Tejun Heo <tj@kernel.org>, Dave Hansen <dave.hansen@intel.com>,
        Tim Chen <tim.c.chen@intel.com>,
        Aubrey Li <aubrey.li@intel.com>
Subject: Re: [RFC] autonuma: Support to scan page table asynchronously
References: <20200418094811.4757-1-sj38.park@gmail.com>
Date:   Mon, 20 Apr 2020 10:32:53 +0800
In-Reply-To: <20200418094811.4757-1-sj38.park@gmail.com> (SeongJae Park's
        message of "Sat, 18 Apr 2020 11:48:11 +0200")
Message-ID: <877dyaubsa.fsf@yhuang-dev.intel.com>
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SeongJae Park <sj38.park@gmail.com> writes:
>
> DAMON allows users to know which address ranges have which access frequency.
> Thus, I think DAMON could be used for detection of hot pages, which will be
> good migration candidates, instead of the NUMA hinting fault based referenced
> pages detection.
>
> The benefits I expect from this change are better accuracy and less overhead.
> As we can know not only referenced pages but hot pages, migration will be more
> effective.

The purpose of AutoNUMA scanning isn't to find the hot pages, but the
pages that are accessed across NUMA node.  PTE accessed bit cannot
provide information of accessing CPU, so it's not enough for AutoNUMA.

Best Regards,
Huang, Ying