linux-kernel - Re: [PATCH 2/3] sched,fair: Fix local starvation

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: <1463839488.24578.45.camel@suse.de>
Date:	Sat, 21 May 2016 16:04:48 +0200
From:	Mike Galbraith <mgalbraith@...e.de>
To:	Peter Zijlstra <peterz@...radead.org>, mingo@...nel.org,
	linux-kernel@...r.kernel.org
Cc:	Pavan Kondeti <pkondeti@...eaurora.org>,
	Ben Segall <bsegall@...gle.com>,
	Matt Fleming <matt@...eblueprint.co.uk>,
	Morten Rasmussen <morten.rasmussen@....com>,
	Paul Turner <pjt@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>, byungchul.park@....com,
	Andrew Hunter <ahh@...gle.com>
Subject: Re: [PATCH 2/3] sched,fair: Fix local starvation

On Tue, 2016-05-10 at 19:43 +0200, Peter Zijlstra wrote:

(Evolution authors must either not do patch review, or use some other
mailer.  Squint hard, this crud really is your patch;)

> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
>  
> @@ -1762,7 +1770,11 @@ void sched_ttwu_pending(void)
>  > 	> while (llist) {
>  > 	> 	> p = llist_entry(llist, struct task_struct, wake_entry);
>  > 	> 	> llist = llist_next(llist);
> -> 	> 	> ttwu_do_activate(rq, p, 0, cookie);
> +> 	> 	> /*
> +> 	> 	>  * See ttwu_queue(); we only call ttwu_queue_remote() when
> +> 	> 	>  * its a x-cpu wakeup.
> +> 	> 	>  */
> +> 	> 	> ttwu_do_activate(rq, p, WF_MIGRATED, cookie);

Wakees that were not migrated/normalized eat an unwanted min_vruntime,
and likely take a size XXL latency hit.  Big box running master bled
profusely under heavy load until I turned TTWU_QUEUE off.

	-Mike