RE: [RFC PATCH v2 20/23] sched/cache: Estimate utilization of the whole thread group

[Jianyong Wu]

Hi Peter,

Sorry for the late reply.

> -----Original Message-----
> From: owner-linux-mm@xxxxxxxxx <owner-linux-mm@xxxxxxxxx> On
> Behalf Of Peter Zijlstra
> Sent: Tuesday, September 1, 2026 10:45 PM
> To: Jianyong Wu <wujianyong@xxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>; Juri Lelli <juri.lelli@xxxxxxxxxx>;
> Vincent Guittot <vincent.guittot@xxxxxxxxxx>; Chen Yu
> <yu.c.chen@xxxxxxxxx>; Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>; Dietmar
> Eggemann <dietmar.eggemann@xxxxxxx>; Steven Rostedt
> <rostedt@xxxxxxxxxxx>; Ben Segall <bsegall@xxxxxxxxxx>; Mel Gorman
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> Prateek Nayak <kprateek.nayak@xxxxxxx>; Shrikanth Hegde
> <sshegde@xxxxxxxxxxxxx>; Phil Auld <pauld@xxxxxxxxxx>; Andrew
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> <david@xxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx; linux-mm@xxxxxxxxx;
> jianyong.wu@xxxxxxxxxxx; Yuan Zhong <zhongyuan@xxxxxxxx>; Huangsj
> <huangsj@xxxxxxxx>; Fengyu Wang <wangfengyu@xxxxxxxx>; Zhiwei Ying
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> Subject: Re: [RFC PATCH v2 20/23] sched/cache: Estimate utilization of the
> whole thread group
> 
> On Fri, Aug 28, 2026 at 10:11:56AM +0800, Jianyong Wu wrote:
> 
> > +					mm_util = mul_u64_u32_div(cpu_util,
> > +							min_t(unsigned long, occ, NICE_0_LOAD),
> > +							NICE_0_LOAD);
> 
> mul_u64_u32_shr(..., NICE_0_LOAD_SHIFT);
> 
> will probably generate better code -- I *think* the mul_u64_u32_div()
> ends up being inline asm and as such cannot optimize the divide
> properly.
> 
Good point, will fix.

Thanks
Jianyong