linux-kernel - Re: [patch] CFS scheduler, -v19

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:	Tue, 17 Jul 2007 19:17:00 +0800
From:	Ian Kent <raven@...maw.net>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Chuck Ebbert <cebbert@...hat.com>,
	Bill Davidsen <davidsen@....com>, linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [patch] CFS scheduler, -v19

On Tue, 2007-07-17 at 09:45 +0200, Ingo Molnar wrote:
> * Ian Kent <raven@...maw.net> wrote:
> 
> > Yes it does and I have two reported bugs so far.
> > 
> > In several places I have code similar to:
> > 
> > wait.tv_sec = time(NULL) + 1;
> > wait.tv_nsec = 0;
> > 
> > signaled = 0;
> > while (!signaled) {
> >         status = pthread_cond_timedwait(&cond, &mutex, &wait);
> >        if (status) {
> >              if (status == ETIMEDOUT)
> >                   break;
> >              fatal(status);
> >       }
> > }
> 
> ah! It passes in a low-res time source into a high-res time interface 
> (pthread_cond_timedwait()). Could you change the time(NULL) + 1 to 
> time(NULL) + 2, or change it to:
> 
> 	gettimeofday(&wait, NULL);
> 	wait.tv_sec++;

OK, I'm with you, hi-res timer.
But even so, how is the time in the past after adding a second.

Is it because I'm not setting tv_nsec when it's close to a second
boundary, and hence your recommendation above?

> 
> does this solve the spinning?

I don't have a system to test this on so I'll try to get one of the
people that logged the problem to test a patch.

> 
> i'm wondering how widespread this is. If automount is the only app doing 
> this then _maybe_ we could get away with it by changing automount?

I'm happy to change automount but that could cause odd version specific
problems for people updating their kernel on an older installed base.

Aaah .. and they'll all blame me!! ;)

Ian


-
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/