linux-kernel - Re: [RFC PATCH 2/3] sched: add yield

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:	Fri, 03 Dec 2010 15:03:30 +0100
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	vatsa@...ux.vnet.ibm.com
Cc:	Rik van Riel <riel@...hat.com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, Avi Kiviti <avi@...hat.com>,
	Ingo Molnar <mingo@...e.hu>,
	Anthony Liguori <aliguori@...ux.vnet.ibm.com>
Subject: Re: [RFC PATCH 2/3] sched: add yield_to function

On Fri, 2010-12-03 at 19:00 +0530, Srivatsa Vaddagiri wrote:
> On Fri, Dec 03, 2010 at 02:23:39PM +0100, Peter Zijlstra wrote:
> > Right, so another approach might be to simply swap the vruntime between
> > curr and p.
> 
> Can't that cause others to stave? For ex: consider a cpu p0 having these tasks:
> 
> p0 ->  A0 B0 A1
> 
> A0/A1 have entered some sort of AB<->BA spin-deadlock, as a result A0 wants to
> direct yield to A1 which wants to direct yield to A0. If we keep swapping their
> runtimes, can't it starve B0?

No, because they do receive service (they spend some time spinning
before being interrupted), so the respective vruntimes will increase, at
some point they'll pass B0 and it'll get scheduled.


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/