linux-kernel - Re: [PATCH 4/4] sched/fair: Do not migrate due to a sync wakeup on exit

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: <20180212200127.GA27522@rhlx01.hs-esslingen.de>
Date:   Mon, 12 Feb 2018 21:01:27 +0100
From:   Andreas Mohr <andi@...as.de>
To:     Mel Gorman <mgorman@...hsingularity.net>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Mike Galbraith <efault@....de>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] sched/fair: Do not migrate due to a sync wakeup on
 exit

Hello,

On Mon, Feb 12, 2018 at 02:58:57PM +0000, Mel Gorman wrote:
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 28c8d9c91955..50442697b455 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -5710,8 +5710,14 @@ wake_affine_idle(int this_cpu, int prev_cpu, int sync)
>  	if (idle_cpu(this_cpu) && cpus_share_cache(this_cpu, prev_cpu))
>  		return idle_cpu(prev_cpu) ? prev_cpu : this_cpu;
>  
> -	if (sync && cpu_rq(this_cpu)->nr_running == 1)
> +	if (sync && cpu_rq(this_cpu)->nr_running == 1) {
> +		/* Avoid tasks exiting pulling parents to new nodes */

Semi-confusing wording (WTH are "pulling parents"? :) - possibly better variant?:
Avoid having exiting tasks pull their parents to new nodes


Good catch, it seems.

HTH,

Andreas Mohr

-- 
GNU/Linux. It's not the software that's free, it's you.