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[2603:7000:9602:8233:6d4:c4ff:fe48:9d05]) by smtp.gmail.com with ESMTPSA id t24sm2399092qto.23.2021.03.11.11.39.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Mar 2021 11:39:37 -0800 (PST) Sender: Tejun Heo Date: Thu, 11 Mar 2021 14:39:36 -0500 From: Tejun Heo To: Michal =?iso-8859-1?Q?Koutn=FD?= Cc: Vipin Sharma , rdunlap@infradead.org, thomas.lendacky@amd.com, brijesh.singh@amd.com, jon.grimm@amd.com, eric.vantassell@amd.com, pbonzini@redhat.com, hannes@cmpxchg.org, frankja@linux.ibm.com, borntraeger@de.ibm.com, corbet@lwn.net, seanjc@google.com, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, gingell@google.com, rientjes@google.com, dionnaglaze@google.com, kvm@vger.kernel.org, x86@kernel.org, cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [Patch v3 0/2] cgroup: New misc cgroup controller Message-ID: References: <20210304231946.2766648-1-vipinsh@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Hello, On Thu, Mar 11, 2021 at 07:58:19PM +0100, Michal Koutný wrote: > > Michal, as you've been reviewing the series, can you please take > > another look and ack them if you don't find anything objectionable? > Honestly, I'm still sitting on the fence whether this needs a new > controller and whether the miscontroller (:-p) is a good approach in the > long term [1]. Yeah, it's a bit of cop-out. My take is that the underlying hardware feature isn't mature enough to have reasonable abstraction built on top of them. Given time, maybe future iterations will get there or maybe it's a passing fad and people will mostly forget about these. In the meantime, keeping them out of cgroup is one direction, a relatively high friction one but still viable. Or we can provide something of a halfway house so that people who have immediate needs can still leverage the existing infrastructure while controlling the amount of time, energy and future lock-ins they take. So, that's misc controller. I'm somewhat ambivalent but we've had multiple of these things popping up in the past several years and containment seems to be a reasonable approach at this point. > [1] Currently, only one thing comes to my mind -- the delegation via > cgroup.subtree_control. The miscontroller may add possibly further > resources whose delegation granularity is bunched up under one entry. Controller enabling and delegation in themselves aren't supposed to have resource or security implications, so I don't think it's a practical problem. Thanks. -- tejun