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Tue, 10 Oct 2023 00:04:15 -0700 (PDT) MIME-Version: 1.0 References: <20231010032833.398033-1-robinlai@tencent.com> In-Reply-To: From: lai bin Date: Tue, 10 Oct 2023 15:04:04 +0800 Message-ID: Subject: Re: [PATCH] sched/wait: introduce endmark in __wake_up_common To: Matthew Wilcox Cc: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, akpm@linux-foundation.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Bin Lai Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 0C2EB40018 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: pxwgc6x8y9tqc6kgr5k9aa3yckox49tr X-HE-Tag: 1696921455-402020 X-HE-Meta: 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 ODqW/r3C rzv8R8wyHNj+C3ITM/BTpU6lgssSq4kzcIWWD+CLHshTpYHVPKFcKKVcPFAjHxTRa7otD6OruGt+56Nu/pO7Zp9yCwO386RMYaZsksd7i6+bJt8E9beGnlotDSdn5LdT3UYAMaaUGH7R7m8bBDR0edjAMglCkUP9jfXIpyKsncbCAggZZNE4drFrX7ecMcrSONpFbDwN46bMvm/+BMQdOhxsn93xq7MzhXKMeXvagOn6jvG2m5XH9eFpDZqq4PkS0r554eXy7Ixm7GBsVHmOALwGDLSdY7yq2+qAHxO1T/V7xEVe45BzctFtj+28De3Idat7yRDmo4P7Qg3snkn8cgG+3+geG+UKhcV8dTXEgN/aWBwK0kAqpzOvG9npuUhWHYkLvXxV3NZZVv49+EIBv2/Nn4zmDJBqRihGONSaY12xZ9mu3UPgzQCSNGfnX2ruS1I+P2CxZBak4Y3oPqwsnq43KhgoYLFTirbiopzPSJ9SJ8yo= X-Bogosity: Ham, tests=bogofilter, spamicity=0.004791, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Yes, you are right. Now that bookmarks weren't actually useful any more, removing bookmarks is a better way to address the livelocks. Matthew Wilcox =E4=BA=8E2023=E5=B9=B410=E6=9C=8810=E6= =97=A5=E5=91=A8=E4=BA=8C 11:58=E5=86=99=E9=81=93=EF=BC=9A > > On Tue, Oct 10, 2023 at 11:28:33AM +0800, Bin Lai wrote: > > Without this patch applied, it can cause the waker to fall into an > > infinite loop in some cases. The commit 2554db916586 ("sched/wait: Brea= k > > up long wake list walk") introduces WQ_FLAG_BOOKMARK to break up long > > wake list walk. When the number of walked entries reach 64, the waker > > will record scan position and release the queue lock, which reduces > > interrupts and rescheduling latency. > > Maybe we could try removing bookmarks instead? There was a thread a > while ago where we agreed they weren't actually useful any more. > > Patches to follow ...