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[209.85.220.41]) by mx.google.com with SMTPS id h136sor6622861ywa.41.2019.04.04.09.39.16 for (Google Transport Security); Thu, 04 Apr 2019 09:39:16 -0700 (PDT) Received-SPF: pass (google.com: domain of hannes@cmpxchg.org designates 209.85.220.41 as permitted sender) client-ip=209.85.220.41; Authentication-Results: mx.google.com; dkim=pass header.i=@cmpxchg-org.20150623.gappssmtp.com header.s=20150623 header.b="N9O/P989"; spf=pass (google.com: domain of hannes@cmpxchg.org designates 209.85.220.41 as permitted sender) smtp.mailfrom=hannes@cmpxchg.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=cmpxchg.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=sVZzefylPUert59vxaZI/oiiATEF9PQOgxdOg2fXoEs=; b=N9O/P989CYq5nDJ+5cfuaXQTyO9yPFp/1/eKojWhp/i7Y2K8efOxl8h5pcHtpCFXpV 2/Fgk3oF02TPKWP0j2FhXquqaxWo7pcBk+LSDFbvbP6L7+AKKu3P8X1Bc/ih1Un5oAHW lidSBfVBXnjoYtvNI8yPV/jeLc7aSm1KqADr4p45hgk+VpTgdmNZgYK7a9ZtS8/nOvWv Ze6qWGbBNiCJZnPke88ZMLvYVM1HMR/817cLJax12DTXw/4xn7MrjL1SOwjZX3E93CRT n9tNcxv2bv+8v9aEkys2lEACvHlf/xG0dxvVaY7Mo0mI/Orl1g12urtpIGjl1Q1vKsWG eLEQ== X-Google-Smtp-Source: APXvYqzilLKYDRMZlOnegsGNrRHGCTLtWjZZcd0Pk6bBZMtt4KU1a29LEu2clZfsFtRi2mMQ7fOucw== X-Received: by 2002:a81:4d8b:: with SMTP id a133mr5725050ywb.122.1554395956113; Thu, 04 Apr 2019 09:39:16 -0700 (PDT) Received: from localhost ([2620:10d:c091:200::1:af4]) by smtp.gmail.com with ESMTPSA id j187sm6563806ywj.32.2019.04.04.09.39.15 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 04 Apr 2019 09:39:15 -0700 (PDT) Date: Thu, 4 Apr 2019 12:39:14 -0400 From: Johannes Weiner To: Zhaoyang Huang Cc: Andrew Morton , Vlastimil Babka , Pavel Tatashin , Joonsoo Kim , David Rientjes , Zhaoyang Huang , Roman Gushchin , Jeff Layton , Matthew Wilcox , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm:workingset use real time to judge activity of the file page Message-ID: <20190404163914.GA4229@cmpxchg.org> References: <1554348617-12897-1-git-send-email-huangzhaoyang@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1554348617-12897-1-git-send-email-huangzhaoyang@gmail.com> User-Agent: Mutt/1.11.4 (2019-03-13) 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 Thu, Apr 04, 2019 at 11:30:17AM +0800, Zhaoyang Huang wrote: > From: Zhaoyang Huang > > In previous implementation, the number of refault pages is used > for judging the refault period of each page, which is not precised as > eviction of other files will be affect a lot on current cache. > We introduce the timestamp into the workingset's entry and refault ratio > to measure the file page's activity. It helps to decrease the affection > of other files(average refault ratio can reflect the view of whole system > 's memory). I don't understand what exactly you're saying here, can you please elaborate? The reason it's using distances instead of absolute time is because the ordering of the LRU is relative and not based on absolute time. E.g. if a page is accessed every 500ms, it depends on all other pages to determine whether this page is at the head or the tail of the LRU. So when you refault, in order to determine the relative position of the refaulted page in the LRU, you have to compare it to how fast that LRU is moving. The absolute refault time, or the average time between refaults, is not comparable to what's already in memory.