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[37.188.180.223]) by smtp.gmail.com with ESMTPSA id z16sm23857077wrl.0.2020.04.15.00.55.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Apr 2020 00:55:32 -0700 (PDT) Date: Wed, 15 Apr 2020 09:55:32 +0200 From: Michal Hocko To: Leonid Moiseichuk Cc: Johannes Weiner , svc lmoiseichuk , vdavydov.dev@gmail.com, tj@kernel.org, lizefan@huawei.com, cgroups@vger.kernel.org, akpm@linux-foundation.org, rientjes@google.com, minchan@kernel.org, vinmenon@codeaurora.org, andriy.shevchenko@linux.intel.com, penberg@kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 0/2] memcg, vmpressure: expose vmpressure controls Message-ID: <20200415075532.GZ4629@dhcp22.suse.cz> References: <20200413215750.7239-1-lmoiseichuk@magicleap.com> <20200414113730.GH4629@dhcp22.suse.cz> <20200414192329.GC136578@cmpxchg.org> 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 Tue 14-04-20 18:12:47, Leonid Moiseichuk wrote: > I do not agree with all comments, see below. > > On Tue, Apr 14, 2020 at 3:23 PM Johannes Weiner wrote: > > > On Tue, Apr 14, 2020 at 12:42:44PM -0400, Leonid Moiseichuk wrote: > > > On Tue, Apr 14, 2020 at 7:37 AM Michal Hocko wrote: > > > > On Mon 13-04-20 17:57:48, svc_lmoiseichuk@magicleap.com wrote: > > > > Anyway, I have to confess I am not a big fan of this. vmpressure turned > > > > out to be a very weak interface to measure the memory pressure. Not > > only > > > > it is not numa aware which makes it unusable on many systems it also > > > > gives data way too late from the practice. > > > > Yes, it's late in the game for vmpressure, and also a bit too late for > > extensive changes in cgroup1. > > > 200 lines just to move functionality from one place to another without > logic change? > There does not seem to be extensive changes. Any user visible API is an big change. We have to maintain any api for ever. So there has to be a really strong reason/use case for inclusion. I haven't heard any strong justification so far. It all seems to me that you are trying to workaround real vmpressure issues by fine tunning parameters and that is almost always a bad reason for a adding a new tunning. -- Michal Hocko SUSE Labs