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[209.85.220.65]) by mx.google.com with SMTPS id d92sor17959199pld.33.2019.05.21.08.45.50 for (Google Transport Security); Tue, 21 May 2019 08:45:51 -0700 (PDT) Received-SPF: pass (google.com: domain of hannes@cmpxchg.org designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@cmpxchg-org.20150623.gappssmtp.com header.s=20150623 header.b=rfl6geAC; spf=pass (google.com: domain of hannes@cmpxchg.org designates 209.85.220.65 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=DCgLiR019LUQfhnXl76ud5P8ct/eu8hvw0HpmgFMVXQ=; b=rfl6geACXaznE893Xv6EgsaoZwgicisSZNkTyws+FFmrjw0cygFwzOxsanbZMxvOf7 6nSazz6qkCSgtzpNrz//Z0sti/qux5BfsEeQpe+9GbUFQ4F7Dmk2r0FnoE/WPfRXN90k 8RRBaIX56/CJcvv0P1a5qYQ1bFdsoK2JKwlFNG+uJDsWnxUChFVNBCQvAXr0vq4KGSph JuAiFZCdMhxHo3BqWgWC3bsYnHIJhGI7oCzQKzV+gVv1tTbiJ9kaSZR453A4nFGOR1+e q8xc6+uuS8Hm84nvH19ohB3e+sXPemZlk/aeTiv3iKYhyfTJWvEpqn/jfzhFmFW28wgf xcvQ== X-Google-Smtp-Source: APXvYqy660k6G3n/CoK0UJH2aQhhfLekgKFUK4qr3XL++igjtjitHM44q7FxegqNyS4YiSWiviy6/A== X-Received: by 2002:a17:902:848c:: with SMTP id c12mr34232829plo.17.1558453550759; Tue, 21 May 2019 08:45:50 -0700 (PDT) Received: from localhost ([2620:10d:c091:500::2:6169]) by smtp.gmail.com with ESMTPSA id 127sm26255492pfc.159.2019.05.21.08.45.49 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 21 May 2019 08:45:49 -0700 (PDT) Date: Tue, 21 May 2019 11:45:48 -0400 From: Johannes Weiner To: Yang Shi Cc: ying.huang@intel.com, mhocko@suse.com, mgorman@techsingularity.net, kirill.shutemov@linux.intel.com, josef@toxicpanda.com, hughd@google.com, shakeelb@google.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [v3 PATCH 1/2] mm: vmscan: remove double slab pressure by inc'ing sc->nr_scanned Message-ID: <20190521154548.GA3687@cmpxchg.org> References: <1558431642-52120-1-git-send-email-yang.shi@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1558431642-52120-1-git-send-email-yang.shi@linux.alibaba.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 Tue, May 21, 2019 at 05:40:41PM +0800, Yang Shi wrote: > The commit 9092c71bb724 ("mm: use sc->priority for slab shrink targets") > has broken up the relationship between sc->nr_scanned and slab pressure. > The sc->nr_scanned can't double slab pressure anymore. So, it sounds no > sense to still keep sc->nr_scanned inc'ed. Actually, it would prevent > from adding pressure on slab shrink since excessive sc->nr_scanned would > prevent from scan->priority raise. > > The bonnie test doesn't show this would change the behavior of > slab shrinkers. > > w/ w/o > /sec %CP /sec %CP > Sequential delete: 3960.6 94.6 3997.6 96.2 > Random delete: 2518 63.8 2561.6 64.6 > > The slight increase of "/sec" without the patch would be caused by the > slight increase of CPU usage. > > Cc: Josef Bacik > Cc: Michal Hocko > Cc: Johannes Weiner > Signed-off-by: Yang Shi Acked-by: Johannes Weiner