linux-kernel - Re: [PATCH] hrtimer: increase clock min delta threshold while interrupt hanging

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: <20081222090545.GA2064@elte.hu>
Date:	Mon, 22 Dec 2008 10:05:45 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Frédéric Weisbecker <fweisbec@...il.com>
Cc:	Frans Pop <elendil@...net.nl>, tglx@...utronix.de,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] hrtimer: increase clock min delta threshold while
	interrupt hanging


* Frédéric Weisbecker <fweisbec@...il.com> wrote:

> > Also, there's min_delta doubling in tick_dev_program_event() itself 
> > too - that interacts with the irq-overload logic:
> >
> > +       dev->min_delta_ns = (unsigned long)try_time.tv64 * 3;
> >
> >        Ingo
> 
> That's what I explained above, the doubling of min delta in 
> tick_dev_program_event() is never reached in my case. And moreover I'm 
> not sure it is ever reached whatever the call sites of 
> tick_dev_program_event() unless min delta has a very low value...

yeah, that looks all rather messy and probably ineffective. Thomas, mind 
to take a look?

Frederic's patch solves a real timer-irq-overload extreme situation so i 
find it rather valuable. Maybe we should do Frederic's patch as-is, have 
the 'softer' min_delta behavior for the usual hrtimer codepaths - and the 
more agressive one for the timer tick only?

	Ingo
--
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/