linux-kernel - Re: [PATCH] Close small window for vsyscall time inconsistencies

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: <alpine.LFD.1.10.0804070826390.3224@apollo.tec.linutronix.de>
Date:	Mon, 7 Apr 2008 08:27:55 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Roman Zippel <zippel@...ux-m68k.org>
cc:	john stultz <johnstul@...ibm.com>,
	Paul Mackerras <paulus@...ba.org>,
	Tony Luck <tony.luck@...el.com>, Ingo Molnar <mingo@...e.hu>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Close small window for vsyscall time inconsistencies

On Mon, 7 Apr 2008, Roman Zippel wrote:
> Hi,
> 
> On Friday 4. April 2008, john stultz wrote:
> 
> > So Thomas and Ingo pointed out to me that they were occasionally seeing
> > small 1ns inconsistencies from clock_gettime() (and more rarely, 1us
> > inconsistencies from gettimeofday() when the 1ns inconsistency occurred
> > on a us boundary)
> 
> What does inconsistency mean?

Time is going backwards by 1us/1nsec.
 
> So instead of shooting in the dark, I'd suggest to collect some
>  numbers first,

That's what we did and John's analysis of the problem is pretty
correct.

Thanks,
	tglx
--
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/