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[213.151.95.130]) by smtp.gmail.com with ESMTPSA id y20sm10509394wmj.23.2020.01.27.06.49.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Jan 2020 06:49:31 -0800 (PST) Date: Mon, 27 Jan 2020 15:49:31 +0100 From: Michal Hocko To: Cong Wang Cc: LKML , Andrew Morton , linux-mm , Mel Gorman , Vlastimil Babka Subject: Re: [PATCH] mm: avoid blocking lock_page() in kcompactd Message-ID: <20200127144931.GM1183@dhcp22.suse.cz> References: <20200109225646.22983-1-xiyou.wangcong@gmail.com> <20200110073822.GC29802@dhcp22.suse.cz> <20200121090048.GG29276@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Sun 26-01-20 11:53:55, Cong Wang wrote: > On Tue, Jan 21, 2020 at 1:00 AM Michal Hocko wrote: > > > > On Mon 20-01-20 14:48:05, Cong Wang wrote: > > > It got stuck somewhere along the call path of mem_cgroup_try_charge(), > > > and the trace events of mm_vmscan_lru_shrink_inactive() indicates this > > > too: > > > > So it seems that you are condending on the page lock. It is really > > unexpected that the reclaim would take that long though. Please try to > > enable more vmscan tracepoints to see where the time is spent. > > Sorry for the delay. I have been trying to collect more data in one shot. > > This is a a typical round of the loop after enabling all vmscan tracepoints: > > <...>-455450 [007] .... 4048595.842992: > mm_vmscan_memcg_reclaim_begin: order=0 may_writepage=1 > gfp_flags=GFP_NOFS|__GFP_HIGHMEM|__GFP_HARDWALL|__GFP_MOVABLE > classzone_idx=4 > <...>-455450 [007] .... 4048595.843012: > mm_vmscan_memcg_reclaim_end: nr_reclaimed=0 This doesn't tell us much though. This reclaim round has taken close to no time. See timestamps. > The whole trace output is huge (33M), I can provide it on request. Focus on reclaim rounds that take a long time and see where it gets you. -- Michal Hocko SUSE Labs