linux-kernel - Re: [PATCH v2] sched/fair: update scale invariance of PELT

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]

Date:   Mon, 1 May 2017 11:00:26 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     mingo@...nel.org, linux-kernel@...r.kernel.org,
        dietmar.eggemann@....com, Morten.Rasmussen@....com,
        yuyang.du@...el.com, pjt@...gle.com, bsegall@...gle.com
Subject: Re: [PATCH v2] sched/fair: update scale invariance of PELT

On Sat, Apr 29, 2017 at 12:09:24AM +0200, Peter Zijlstra wrote:
> On Mon, Apr 10, 2017 at 11:18:29AM +0200, Vincent Guittot wrote:
> > +++ b/include/linux/sched.h
> > @@ -313,6 +313,7 @@ struct load_weight {
> >   */
> >  struct sched_avg {
> >  	u64				last_update_time;
> > +	u64				stolen_idle_time;
> >  	u64				load_sum;
> >  	u32				util_sum;
> >  	u32				period_contrib;
> 
> > +		if (sa->util_sum < (LOAD_AVG_MAX * 1000)) {
> > +			/*
> > +			 * Add the idle time stolen by running at lower compute
> > +			 * capacity
> > +			 */
> > +			delta += sa->stolen_idle_time;
> > +		}
> > +		sa->stolen_idle_time = 0;
> 
> 
> So I was wondering if stolen_idle_time really needs to be a u64. Afaict
> we'll be at LOAD_AVG_MAX after LOAD_AVG_MAX_N periods, or LOAD_AVG_MAX_N
> * LOAD_AVG_PERIOD time, which ends up being 11040.

* 1024 or course, but still easily fits in u32.