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[71.184.117.43]) by smtp.gmail.com with ESMTPSA id j7sm17172579qtc.73.2019.10.23.05.42.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 23 Oct 2019 05:42:40 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable From: Qian Cai Mime-Version: 1.0 (1.0) Subject: Re: [PATCH] mm/vmstat: Reduce zone lock hold time when reading /proc/pagetypeinfo Date: Wed, 23 Oct 2019 08:42:40 -0400 Message-Id: References: <20191023095607.GE3016@techsingularity.net> Cc: Michal Hocko , Mel Gorman , Waiman Long , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Johannes Weiner , Roman Gushchin , Vlastimil Babka , Konstantin Khlebnikov , Jann Horn , Song Liu , Greg Kroah-Hartman , Rafael Aquini In-Reply-To: <20191023095607.GE3016@techsingularity.net> To: Mel Gorman X-Mailer: iPhone Mail (17A878) 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 Oct 23, 2019, at 5:56 AM, Mel Gorman wrote: >=20 > Again, the cost is when reading a proc file. =46rom what Andrew said, > the lock is necessary to safely walk the list but if anything. I would > be ok with limiting the length of the walk but honestly, I would also > be ok with simply deleting the proc file. The utility for debugging a > problem with it is limited now (it was more important when fragmentation > avoidance was first introduced) and there is little an admin can do with > the information. I can't remember the last time I asked for the contents > of the file when trying to debug a problem. There is a possibility that > someone will complain but I'm not aware of any utility that reads the > information and does something useful with it. In the unlikely event > something breaks, the file can be re-added with a limited walk. Agree. It is better to remove this file all together in linux-next first for= a while to see if anyone complains loudly.=