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[72.28.8.195]) by smtp.gmail.com with ESMTPSA id s130sm5055078qka.91.2020.12.04.07.45.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Dec 2020 07:45:53 -0800 (PST) Sender: Tejun Heo Date: Fri, 4 Dec 2020 10:45:25 -0500 From: Tejun Heo To: Josh Don Cc: Peter Zijlstra , "Joel Fernandes (Google)" , Nishanth Aravamudan , Julien Desfossez , Tim Chen , Vineeth Pillai , Aaron Lu , Aubrey Li , Thomas Gleixner , linux-kernel , mingo@kernel.org, torvalds@linux-foundation.org, fweisbec@gmail.com, Kees Cook , Greg Kerr , Phil Auld , Valentin Schneider , Mel Gorman , Pawan Gupta , Paolo Bonzini , vineeth@bitbyteword.org, Chen Yu , Christian Brauner , Agata Gruza , Antonio Gomez Iglesias , graf@amazon.com, konrad.wilk@oracle.com, dfaggioli@suse.com, Paul Turner , Steven Rostedt , Patrick Bellasi , benbjiang@tencent.com, Alexandre Chartre , James.Bottomley@hansenpartnership.com, OWeisse@umich.edu, Dhaval Giani , Junaid Shahid , Jesse Barnes , chris.hyser@oracle.com, Ben Segall , Hao Luo , Tom Lendacky , Aubrey Li , "Paul E. McKenney" , Tim Chen , Oleg Rombakh Subject: Re: [PATCH -tip 26/32] sched: Add a second-level tag for nested CGroup usecase Message-ID: References: <20201117232003.3580179-1-joel@joelfernandes.org> <20201117232003.3580179-27-joel@joelfernandes.org> <20201125134237.GZ2414@hirez.programming.kicks-ass.net> <20201202080211.GD3021@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Thu, Dec 03, 2020 at 04:51:42PM -0800, Josh Don wrote: > > So me the color thing reads like an end-run around the cgroup hierarchy. > > Restructuring the cgroup resource hierarchy to incorporate the trust > domains is not necessarily trivial (as is the case for us). I agree > though that that would be the ideal correct solution from the cgroup > hierarchy perspective. Yeah, it sure isn't. We (FB) had to go through a couple iterations and it's looking like we need another adjustment, so I fully agree that these are painful but at the same time I don't think it's difficult to see that how piling up workarounds in the lowest layer is not the right thing to do. The workarounds you guys need would be different from what we or others would need. The kernel can't be maintained in any sustainable manner if we keep piling on disjoint workarounds on it. Please consider long term trajectory when proposing interface changes which often boils down to identifying the core features which must be supported by the interface. Thanks. -- tejun