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From: Kayra Cizmeci <kayracizmeci@gmail.com>
To: jackzxcui1989@163.com
Cc: bsegall@google.com, dietmar.eggemann@arm.com,
	juri.lelli@redhat.com, kprateek.nayak@amd.com,
	linux-kernel@vger.kernel.org, mgorman@suse.de, mingo@redhat.com,
	peterz@infradead.org, rostedt@goodmis.org,
	vincent.guittot@linaro.org, vschneid@redhat.com
Subject: Re: [RFC PATCH RESEND 05/10] sched/fair: Introduce select_task_rq_fair_thin() to select rq when LB_PROMOTE
Date: Thu, 10 Sep 2026 15:00:29 +0300	[thread overview]
Message-ID: <20260910120029.1207437-1-kayracizmeci@gmail.com> (raw)
In-Reply-To: <20260910042950.1619727-6-jackzxcui1989@163.com>

Hello Xin,

> Testing has shown that in our system with 18 CPUs running at 2.1GHz, where
> the first three sd_llc domains each contains 4 CPUs and the last sd_llc
> contains 2 CPUs, under same fillback scenario, select_task_rq_fair_thin()
> executes 25% faster than the original select_task_rq_fair(). It saves 22ms
> over a 10-second period, with this optimization accounting for 0.174% of
> total system time. Additionally, we measured the execution time of
> update_idle_cpu_scan, which took 0.5ms over the same 10-second period. If
> we use select_task_rq_fair_thin() instead, this time can be eliminated,
> accounting for 0.04% of total system time. Therefore, the overall
> optimization contributes to a reduction of 0.214% of total system time.

Okay. Can you specify which tests you ran or what you used? If you can?

Thanks,
Kayra


  parent reply	other threads:[~2026-09-10 12:00 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-10  4:29 [RFC PATCH RESEND 00/10] sched/fair: A series of load balance patches to improve real-time performance of CFS tasks Xin Zhao
2026-09-10  4:29 ` [RFC PATCH RESEND 01/10] sched/fair: Do not set_rd_overloaded() if rd->online != env->cpus Xin Zhao
2026-09-10  8:30   ` K Prateek Nayak
2026-09-10 13:45     ` Vincent Guittot
2026-09-11  1:06     ` Xin Zhao
2026-09-11  6:21       ` K Prateek Nayak
2026-09-12  1:46         ` Xin Zhao
2026-09-12  1:53         ` Xin Zhao
2026-09-10  4:29 ` [RFC PATCH RESEND 02/10] scbed/fair: Remove duplicate check for busiest_cpu in active_load_balance_cpu_stop() Xin Zhao
2026-09-10 11:41   ` Kayra Cizmeci
2026-09-11  0:22     ` Xin Zhao
2026-09-11  9:20       ` Kayra Cizmeci
2026-09-10  4:29 ` [RFC PATCH RESEND 03/10] sched/fair: Clear active_balance at the end of active_load_balance_cpu_stop() Xin Zhao
2026-09-10  8:09   ` K Prateek Nayak
2026-09-10 14:15     ` Xin Zhao
2026-09-10  4:29 ` [RFC PATCH RESEND 04/10] sched/fair: Add LB_PROMOTE feature to enhance real-time performance of fair tasks Xin Zhao
2026-09-11 12:32   ` Vincent Guittot
2026-09-12  4:28     ` Xin Zhao
2026-09-10  4:29 ` [RFC PATCH RESEND 05/10] sched/fair: Introduce select_task_rq_fair_thin() to select rq when LB_PROMOTE Xin Zhao
2026-09-10  8:19   ` Vincent Guittot
2026-09-10 14:39     ` Xin Zhao
2026-09-10 15:31       ` Vincent Guittot
2026-09-10 15:56         ` Xin Zhao
2026-09-11 12:27           ` Vincent Guittot
2026-09-12  4:08             ` Xin Zhao
2026-09-15 11:56               ` Vincent Guittot
2026-09-15 21:43                 ` Kayra Cizmeci
2026-09-10 12:00   ` Kayra Cizmeci [this message]
2026-09-10 14:56     ` Xin Zhao
2026-09-15 18:19       ` Kayra Cizmeci
2026-09-10  4:29 ` [RFC PATCH RESEND 06/10] sched/fair: Modify active_load_balance_cpu_stop() to accommodate more scenarios Xin Zhao
2026-09-10  4:29 ` [RFC PATCH RESEND 07/10] sched/fair: Trigger active balance if a CFS task is preempted when LB_PROMOTE Xin Zhao
2026-09-10  4:29 ` [RFC PATCH RESEND 08/10] sched/fair: Do not check avg_idle to prematurely exit newly idle " Xin Zhao
2026-09-10  4:29 ` [RFC PATCH RESEND 09/10] sched/fair: Not goto more_balance if newly idle and has pending task when LBF_NEED_BREAK Xin Zhao
2026-09-10  4:29 ` [RFC PATCH RESEND 10/10] sched/fair: Strive to find a task to migrate if newly idle when LB_PROMOTE Xin Zhao

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