linux-kernel - Re: [PATCH 19/19] sched/fair: Add user control to adjust the tolerance of cache-aware scheduling

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CANCG0Gfud=g2zUQrDJUipiP0-id0_Jv4kkoWGnyYvwDJAR+gdw@mail.gmail.com>
Date: Wed, 29 Oct 2025 09:07:04 +0100
From: Aaron Lu <ziqianlu@...edance.com>
To: Tim Chen <tim.c.chen@...ux.intel.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	K Prateek Nayak <kprateek.nayak@....com>, "Gautham R . Shenoy" <gautham.shenoy@....com>, 
	Chen Yu <yu.c.chen@...el.com>, Vincent Guittot <vincent.guittot@...aro.org>, 
	Juri Lelli <juri.lelli@...hat.com>, Dietmar Eggemann <dietmar.eggemann@....com>, 
	Steven Rostedt <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>, 
	Valentin Schneider <vschneid@...hat.com>, Madadi Vineeth Reddy <vineethr@...ux.ibm.com>, 
	Hillf Danton <hdanton@...a.com>, Shrikanth Hegde <sshegde@...ux.ibm.com>, 
	Jianyong Wu <jianyong.wu@...look.com>, Yangyu Chen <cyy@...self.name>, 
	Tingyin Duan <tingyin.duan@...il.com>, Vern Hao <vernhao@...cent.com>, 
	Len Brown <len.brown@...el.com>, Aubrey Li <aubrey.li@...el.com>, 
	Zhao Liu <zhao1.liu@...el.com>, Chen Yu <yu.chen.surf@...il.com>, 
	Libo Chen <libo.chen@...cle.com>, Adam Li <adamli@...amperecomputing.com>, 
	Tim Chen <tim.c.chen@...el.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 19/19] sched/fair: Add user control to adjust the
 tolerance of cache-aware scheduling

On Sat, Oct 11, 2025 at 11:24:56AM -0700, Tim Chen wrote:
... ...
> +static inline int get_sched_cache_cap_scale(void)
> +{
> +	return (llc_overload_pct / cpu_smt_num_threads);
> +}
> +
... ...
> @@ -9749,7 +9811,7 @@ static inline int task_is_ineligible_on_dst_cpu(struct task_struct *p, int dest_
>   * (default: ~50%)
>   */
>  #define fits_llc_capacity(util, max)	\
> -	((util) * 100 < (max) * llc_overload_pct)
> +	((util) * 100 < (max) * get_sched_cache_cap_scale())
>

With this change, fits_llc_capacity() would be false if util is just 1/4
of max(which is llc's total cpu capacity), is this intended?