linux-kernel - Re: [patch, v2.6.22-rc6] sys

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: <1182877164.1437.49.camel@localhost>
Date:	Tue, 26 Jun 2007 09:59:24 -0700
From:	john stultz <johnstul@...ibm.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Mark Lord <lkml@....ca>, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [patch, v2.6.22-rc6] sys_time() speedup

On Tue, 2007-06-26 at 16:58 +0200, Ingo Molnar wrote:
> * Mark Lord <lkml@....ca> wrote:
> 
> > Ingo Molnar wrote:
> > >Subject: [patch] sys_time() speedup
> > >From: Ingo Molnar <mingo@...e.hu>
> > >
> > >improve performance of sys_time(). sys_time() returns time in seconds, 
> > >but it does so by calling do_gettimeofday() and then returning the 
> > >tv_sec portion of the GTOD time. But the data structure "xtime", which 
> > >is updated by every timer/scheduler tick, already offers HZ granularity 
> > >time.
> > 
> > How well synchronized is xtime with real-time ?
> 
> it's updated by every jiffy.

Well, NTP_INTERVAL_LENGTH to be specific which is every jiffie with one
exception: With dynticks this is a bit more complicated, and xtime is
updated only twice a second.

thanks
-john

-
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/