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Tue, 24 Mar 2020 06:23:51 -0700 (PDT) Received: from localhost ([2620:10d:c092:180::1:8734]) by smtp.gmail.com with ESMTPSA id w7sm29792149wrr.60.2020.03.24.06.23.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Mar 2020 06:23:51 -0700 (PDT) Date: Tue, 24 Mar 2020 13:23:50 +0000 From: Chris Down To: Hui Zhu Cc: hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com, akpm@linux-foundation.org, hughd@google.com, yang.shi@linux.alibaba.com, kirill@shutemov.name, dan.j.williams@intel.com, aneesh.kumar@linux.ibm.com, sean.j.christopherson@intel.com, thellstrom@vmware.com, guro@fb.com, shakeelb@google.com, tj@kernel.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, Hui Zhu Subject: Re: [PATCH] mm, memcg: Add memory.transparent_hugepage_disabled Message-ID: <20200324132350.GA7528@chrisdown.name> References: <1585045916-27339-1-git-send-email-teawater@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <1585045916-27339-1-git-send-email-teawater@gmail.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: Hui Zhu writes: >/sys/kernel/mm/transparent_hugepage/enabled is the only interface to >control if the application can use THP in system level. >Sometime, we would not want an application use THP even if >transparent_hugepage/enabled is set to "always" or "madvise" because >thp may need more cpu and memory resources in some cases. > >This commit add a new interface memory.transparent_hugepage_disabled >in memcg. >When it set to 1, the application inside the cgroup cannot use THP >except dax. I'm against this patch even in the abstract -- this adds an extremely niche use case to a general interface, and there are plenty of ways to already indicate THP preference. Perhaps there is some new interface desirable for your use case, but adding a new global file to memcg certainly isn't it.