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Sun, 13 Sep 2026 22:27:07 -0700 (PDT) From: Kayra Cizmeci To: yu.c.chen@intel.com Cc: brauner@kernel.org, bsegall@google.com, chen.yu@linux.dev, dietmar.eggemann@arm.com, imv4bel@gmail.com, jack@suse.cz, juri.lelli@redhat.com, kayracizmeci@gmail.com, kees@kernel.org, kprateek.nayak@amd.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mgorman@suse.de, mingo@redhat.com, peterz@infradead.org, qyousef@layalina.io, ricardo.neri-calderon@linux.intel.com, rostedt@goodmis.org, srikar@linux.ibm.com, sshegde@linux.ibm.com, tim.c.chen@linux.intel.com, vincent.guittot@linaro.org, vineethr@linux.ibm.com, viro@zeniv.linux.org.uk, vschneid@redhat.com, wanglu.priv@gmail.com, yi1.lai@intel.com, zhanxusheng1024@gmail.com, zhanxusheng@xiaomi.com, ziqianlu@bytedance.com Subject: Re: [PATCH 1/4] sched/cache: Keep nr_pref_llc_running in the runnable domain Date: Mon, 14 Sep 2026 08:27:03 +0300 Message-ID: <20260914052703.1286495-1-kayracizmeci@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: D825C140008 X-Stat-Signature: 9y3i58uwhkitaq8nsgemche3rbtjyrgs X-HE-Tag: 1789363629-851236 X-HE-Meta: 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 YTGfrxOy 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hello Chen, > Hi Kayra, > I had a try according to your suggestion. It seems that the code becomes more complex > and brings more headache :-( due to several corner cases. The current version is a simpler > version with less code IMO. But I agree it looks a little hard to catch up with, so I added > some comments around account_llc_dequeue() and adjusted the code sequence of clear_delayed() > to make it easier to understand. Tim, could you please help check if this makes sense? I can't read your magnificent comment right now, I'm in a hurry. Sorry :-(. (But I will :>) > @@ -6415,23 +6465,18 @@ static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq); > static void set_delayed(struct sched_entity *se) > { > - /* > - * Drop a task leaving the runnable set. Must run before sched_delayed > - * is set, or task_pref_llc_runnable() would already exclude it; > - * clear_delayed() mirrors this after clearing the flag. > - */ > - if (entity_is_task(se)) > - pref_llc_running_dec(rq_of(cfs_rq_of(se)), task_of(se)); > - > - se->sched_delayed = 1; >- > /* > * Delayed se of cfs_rq have no tasks queued on them. > * Do not adjust h_nr_runnable since __dequeue_task() > * will account it for blocked tasks. > */ > - if (!entity_is_task(se)) > + if (!entity_is_task(se)) { > + se->sched_delayed = 1; > return; > + } > + > + pref_llc_running_dec(rq_of(cfs_rq_of(se)), task_of(se)); > + se->sched_delayed = 1; > > for_each_sched_entity(se) { > struct cfs_rq *cfs_rq = cfs_rq_of(se); Yeah, I think this is cleaner. I didn't read the comment tho :>. Thanks, Kayra :--)