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[195.135.220.15]) by mx.google.com with ESMTPS id p14si1701069eda.200.2019.06.06.07.44.44 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 06 Jun 2019 07:44:44 -0700 (PDT) Received-SPF: pass (google.com: domain of mhocko@suse.com designates 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=pass (google.com: domain of mhocko@suse.com designates 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@suse.com 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 41D40AF1C; Thu, 6 Jun 2019 14:44:44 +0000 (UTC) Date: Thu, 6 Jun 2019 16:44:39 +0200 From: Michal Hocko To: Yafang Shao Cc: Andrew Morton , Bharath Vedartham , Linux MM , shaoyafang@didiglobal.com Subject: Re: [PATCH v4 0/3] mm: improvements in shrink slab Message-ID: <20190606144439.GA12311@dhcp22.suse.cz> References: <1559816080-26405-1-git-send-email-laoar.shao@gmail.com> <20190606111755.GB15779@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 Thu 06-06-19 22:18:41, Yafang Shao wrote: [...] > Well, seems when we introduce new feature for page relciam, we always > ignore the node reclaim path. Yes, node reclaim is quite weird and I am not really sure whether we still have many users these days. It used to be mostly driven by artificial benchmarks which highly benefit from the local node access. We have turned off its automatic enabling when there are nodes with higher access latency quite some time ago without anybody noticing actually. > Regarding node reclaim path, we always turn it off on our servers, > because we really found some latency spike caused by node reclaim > (the reason why node reclaim is turned on is not clear). Yes, that was the case and the reason it is not enabled by default. > The reason I expose node reclaim details to userspace is because the user > can set node reclaim details now. Well, just because somebody _can_ enable it doesn't sound like a sufficient justification to expose even more implementation details of this feature. I am not really sure there is a strong reason to touch the code without a real usecase behind. -- Michal Hocko SUSE Labs