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[24.6.216.183]) by smtp.gmail.com with ESMTPSA id z1-20020a170903018100b0016f0d6213a5sm1527879plg.2.2022.08.04.15.17.45 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 04 Aug 2022 15:17:46 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.120.41.1.1\)) Subject: Re: [PATCH v2 0/2] mm: Remember a/d bits for migration entries From: Nadav Amit In-Reply-To: <20220804203952.53665-1-peterx@redhat.com> Date: Thu, 4 Aug 2022 15:17:44 -0700 Cc: Linux MM , LKML , Huang Ying , Andrea Arcangeli , David Hildenbrand , Minchan Kim , Andrew Morton , Vlastimil Babka , Hugh Dickins , Andi Kleen , "Kirill A . Shutemov" Content-Transfer-Encoding: 7bit Message-Id: <8FBBFD68-3315-48D6-B318-4AA5A170C0C8@gmail.com> References: <20220804203952.53665-1-peterx@redhat.com> To: Peter Xu X-Mailer: Apple Mail (2.3696.120.41.1.1) ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1659651469; a=rsa-sha256; cv=none; b=y3tzFhBIUM1XutKDxsaLKEYLQxFcIEGaDriKd8MjpC72GwhX5RknZHMR28m22u1MQrxrAR +Wh2TzD9zsZq/VwmC1OcYHq7Ye1pTuh0AiN1VfmUdhud56ocibJ01+LV7fDXe5qEzYs1RU psk93MOSFpZa4a4uQ0NRlsYlXGWf25k= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=ED+ZBw0+; spf=pass (imf07.hostedemail.com: domain of nadav.amit@gmail.com designates 209.85.210.178 as permitted sender) smtp.mailfrom=nadav.amit@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1659651469; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=sV7vlp9vVqtESovTZq4J4qUrClPc07IPwMZZmtZmWxI=; b=V8ivY5NWP8alXNPfqoC8elgxh4rcTusjWiSr4LVMPMva2g0WahCdaBonQ1z+/NLv1sF3q8 2+9QloXtMJRb2FXGl1dgSO3Zc9KtSeJFcAeKlk6EQuMxtfDcOIjneooMYEOGl7IQD6HwKu O5pdNziZgokgdtVOfYRFwOkmCTWSa44= X-Rspamd-Server: rspam04 X-Stat-Signature: 4i736o1es7eqhoaqxy5y4ochd3emjjar Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=ED+ZBw0+; spf=pass (imf07.hostedemail.com: domain of nadav.amit@gmail.com designates 209.85.210.178 as permitted sender) smtp.mailfrom=nadav.amit@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Rspamd-Queue-Id: BEEA14000D X-Rspam-User: X-HE-Tag: 1659651469-75872 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Aug 4, 2022, at 1:39 PM, Peter Xu wrote: > (1) Page Idle Tracking > > Before this series, idle tracking can cause false negative if an accessed > page got migrated, since after migration the young bit will get lost. > After this series, it'll be better in that after migration young bit will > be persisted, so it'll be able to be detected correctly by page idle > logic when walking the pgtable. > > However there's still nothing done when page idle reset was carried out > during migration procedure in progress, but that should be a separate > topic to be addressed (e.g. to teach rmap pgtable walk code to be able to > walk with both present ptes and migration ptes). IIUC, when a migration entry is set page_remove_rmap() is called by try_to_migrate_one(), so improving page-idle accuracy should be done in a different way.