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Wed, 22 Mar 2023 21:10:32 -0700 (PDT) MIME-Version: 1.0 References: <20230323040037.2389095-1-yosryahmed@google.com> In-Reply-To: <20230323040037.2389095-1-yosryahmed@google.com> From: Shakeel Butt Date: Wed, 22 Mar 2023 21:10:21 -0700 Message-ID: Subject: Re: [RFC PATCH 0/7] Make rstat flushing IRQ and sleep friendly To: Yosry Ahmed Cc: Tejun Heo , Josef Bacik , Jens Axboe , Zefan Li , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Andrew Morton , Vasily Averin , cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, bpf@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 2478040014 X-Rspam-User: X-Stat-Signature: rup6k8raj39ij6xjuj33xaq7667r8bot X-HE-Tag: 1679544632-817228 X-HE-Meta: U2FsdGVkX19dOBlUGgWhELoTRifFGmIIWRc/yxx3rxw8bTyNuQdUycS9RzaNZStWMqPtT+087Qr74Idaw0znq3PSHbG7k8sdWnnGH0aXV4sMRmPXcZlwXkpmD9hg88OZw+kwWEmDGhheFNuW6dlbOjhpal3e6t2Baem9G9rUPPD3zEjBsX9DQAgr8NgREqU3uj6qF0kiwVmtrfbswOUuG30L2ty84D9OelYX3DmL7p8NUIoTSscSxfMXZIQakmahU/8cLkpgp47ZtpEBCoMHTTIfuGbuJuSQNvnxNV+5GCyL5tb2Ywlt/8kgn7QAXYVkU+Kvrd9cPb+w/fVnInBhwn03FLUrBBgqsRUFKEAqn8dA1DFsCmBivHsRw2+amzMmGcMAIAVBsvD0fbFhvHI+3vJQx9FY+uT5I8fbvPVXoMfP3VMfKRxdDKThh0+stFOeySjhsxD/xnBIxxACzcd++Uw1ZtfxZEGNa7xw+jSFoJW+S8F0m3gbiFntq4Mygy+gMSw2dcWdhdCeOjESBAU3sx6gu0/IZcyLKMGtOdBfzS+Dn5NFnFzNTTIl4koR2PqosBcIZrTN1G2pmxFKdKGngXph1ymMh/yABxcAEeaHsUGWxddlgvLUL8WWta6z0Zz/VoKV7BFyQ+XaxWI4XLiCZo3G+cjpk0ZAIoTK8fwELB020XMpe+qvOzzPtr0PB2i5jVEM76j3ltW0GNZM61tWXnQLSCpIj6D2kaei1P4+cywiMRDv9UEeuWIQ2zGHGMSp5CP/VbpWlf4s8Ov+wBsN+usGcGDicCKI234SJeXdw34Nd1FN6EZsdZy58LuAI9H6BBsLi1oUak8EkZU5r0mofBXyblC4OzPgE/U5ay6OOe4m4hrJS7wPr7ASfXo6iZYYDBfUlBEedHKRMF62fpKf+XHXNB7S8mcV/QqIMn1v2ajEX++fbCys9w49FSugTWlkrZtzgCx8w7z9/S6d8yS Fw0yffCi u9D3cmEj0FWLIQ4gGc/0UNwi2BsoIoiZAVR1Eyaqb4J0Ed5E3FAJAKHvZXN3+r8F+ekm8/kMLgt0YDuzPwk8UR0GV7xrpG7CUVZDfrZg47VdwSpfVroi89Xb4RImoEuW72Q+8xWNDVod9q0yKrXOaIa3prW6sW6jVBtFCnEphIZdDQeU2tYqwKJDmoPhDPnkfNLxKC6bfPjq6DyBIGEDQ+BaqlSPM+WT8djAQYXItIBt1gZ0PMPr05eG3waebPn99bhyd13C593iq8Lo= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000051, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Mar 22, 2023 at 9:00=E2=80=AFPM Yosry Ahmed = wrote: > > Currently, if rstat flushing is invoked using the irqsafe variant > cgroup_rstat_flush_irqsafe(), we keep interrupts disabled and do not > sleep for the entire flush operation, which is O(# cpus * # cgroups). > This can be rather dangerous. > > Not all contexts that use cgroup_rstat_flush_irqsafe() actually cannot > sleep, and among those that cannot sleep, not all contexts require > interrupts to be disabled. Too many negations in the above sentence is making it very confusing.