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[37.188.130.62]) by smtp.gmail.com with ESMTPSA id n2sm122205wrq.74.2020.04.20.10.03.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Apr 2020 10:03:19 -0700 (PDT) Date: Mon, 20 Apr 2020 19:03:18 +0200 From: Michal Hocko To: Tejun Heo Cc: Shakeel Butt , Jakub Kicinski , Andrew Morton , Linux MM , Kernel Team , Johannes Weiner , Chris Down , Cgroups Subject: Re: [PATCH 0/3] memcg: Slow down swap allocation as the available space gets depleted Message-ID: <20200420170318.GV27314@dhcp22.suse.cz> References: <20200417162355.GA43469@mtj.thefacebook.com> <20200417173615.GB43469@mtj.thefacebook.com> <20200417193539.GC43469@mtj.thefacebook.com> <20200417225941.GE43469@mtj.thefacebook.com> <20200420164740.GF43469@mtj.thefacebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200420164740.GF43469@mtj.thefacebook.com> 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 Mon 20-04-20 12:47:40, Tejun Heo wrote: [...] > > Coming back to this path series, to me, it seems like the patch series > > is contrary to the vision you are presenting. Though the users are not > > setting memory.[high|max] but they are setting swap.max and this > > series is asking to set one more tunable i.e. swap.high. The approach > > more consistent with the presented vision is to throttle or slow down > > the allocators when the system swap is near full and there is no need > > to set swap.max or swap.high. I have the same impression as Shakeel here. The overall information we have here is really scarce. > It's a piece of the puzzle to make memory protection work comprehensively. > You can argue that the fact swap isn't protection based is against the > direction but I find that argument rather facetious as swap is quite > different resource from memory and it's not like I'm saying limits shouldn't > be used at all. There sure still are missing pieces - ie. slowing down on > global depletion, but that doesn't mean swap.high isn't useful. I have asked about the semantic of this know already and didn't really get any real answer. So how does swap.high fit into high limit semantic when it doesn't act as a limit. Considering that we cannot reclaim swap space I find this really hard to grasp. We definitely need more information here! -- Michal Hocko SUSE Labs