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[195.135.220.15]) by mx.google.com with ESMTPS id v28si403475edc.12.2019.05.13.14.45.05 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 13 May 2019 14:45:05 -0700 (PDT) Received-SPF: softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id A9351AC94; Mon, 13 May 2019 21:45:04 +0000 (UTC) Date: Mon, 13 May 2019 23:45:03 +0200 From: Michal Hocko To: Yang Shi Cc: ying.huang@intel.com, hannes@cmpxchg.org, mgorman@techsingularity.net, kirill.shutemov@linux.intel.com, hughd@google.com, shakeelb@google.com, william.kucharski@oracle.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [v2 PATCH] mm: vmscan: correct nr_reclaimed for THP Message-ID: <20190513214503.GB25356@dhcp22.suse.cz> References: <1557505420-21809-1-git-send-email-yang.shi@linux.alibaba.com> <20190513080929.GC24036@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) 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 Mon 13-05-19 14:09:59, Yang Shi wrote: [...] > I think we can just account 512 base pages for nr_scanned for > isolate_lru_pages() to make the counters sane since PGSCAN_KSWAPD/DIRECT > just use it. > > And, sc->nr_scanned should be accounted as 512 base pages too otherwise we > may have nr_scanned < nr_to_reclaim all the time to result in false-negative > for priority raise and something else wrong (e.g. wrong vmpressure). Be careful. nr_scanned is used as a pressure indicator to slab shrinking AFAIR. Maybe this is ok but it really begs for much more explaining than "it should be fine". This should have happened when THP swap out was implemented... -- Michal Hocko SUSE Labs