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Thu, 18 Jul 2024 02:22:09 +0000 (UTC) Message-ID: <0addf17f-1dc8-40f1-970a-9a3d44b14d71@redhat.com> Date: Wed, 17 Jul 2024 22:22:08 -0400 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm, memcg: cg2 memory{.swap,}.peak write handlers To: Tejun Heo Cc: David Finkel , Johannes Weiner , Michal Hocko , Muchun Song , Andrew Morton , core-services@vimeo.com, Jonathan Corbet , Roman Gushchin , Shuah Khan , Zefan Li , cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Shakeel Butt References: <20240715203625.1462309-1-davidf@vimeo.com> <20240715203625.1462309-2-davidf@vimeo.com> <20240717170408.GC1321673@cmpxchg.org> <20240717204453.GD1321673@cmpxchg.org> <85a67b00-9ae7-42a1-87e0-19b5563b9a0f@redhat.com> Content-Language: en-US From: Waiman Long In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: C84761C001F X-Stat-Signature: n5nspbcauzpoe9kuzkm4d7gr1m6u8kur X-Rspam-User: X-HE-Tag: 1721269343-40650 X-HE-Meta: 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 vv+fgX/v 5LDaegVow2ItcVQhu484KFgU0/Y/SBSPaTxESmcLRZBZXOURcVjgSjRrFFsCI19k4gg8cYjCmB0av+splrtyLOaYQiZ0IfayIkx1kWlkphQIWMIS6yzuY/f/fsKU+P47qGi1cUxrdPzL/1PHqzxyQYNq1MNQ4njsMXXhhT8qlgHgaAcCdmQ1OEJmazCIcaS1WuBpuBuTWQwooF/YEGmRCCgU/RBxSE+sH7F9uBwpIKn3aLYgZLF4Q01E+38jImrq5wfRNDeUB19vZnzAQ3QsYiPX1h19njux5WSluHU0sWohFAP0= 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: List-Subscribe: List-Unsubscribe: On 7/17/24 21:24, Tejun Heo wrote: > On Wed, Jul 17, 2024 at 07:48:40PM -0400, Waiman Long wrote: > ... >> How about letting .peak shows two numbers? The first one is the peak since >> the creation of the cgroup and cannot be reset. The second one is a local >> maximum that can be reset to 0. We just to keep track of one more counter >> that should be simple enough to implement. > What Johannes suggested seems to hit all the marks - it's efficient and > relatively simple, the overhead is only on the users of the facility, and > flexible in a straightforward manner. I have a hard time buying the argument > that it's more difficult to use - the benefit to cost ratio seems pretty > clear. Given that, I'm not sure why we'd want to add something fishy that > can lead to longterm problems. On second thought, it is a change in the user interface that may break existing apps that use the peak file. So it is probably better to go with Johannes' suggestion. Thanks, Longman