linux-kernel - RE: Possible CPU_IDLE bug [WAS: Re: Timer unstability on when using C2 and deeper sleep states (Dell Latitude XT)]

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: <1218720507.4545.9.camel@localhost>
Date:	Thu, 14 Aug 2008 15:28:27 +0200
From:	Milan Plzik <milan.plzik@...il.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: Possible CPU_IDLE bug [WAS: Re: Timer unstability on when
	using C2 and deeper sleep states (Dell Latitude XT)]

On Št, 2008-08-14 at 13:40 +0200, Milan Plzik wrote:
> On Št, 2008-08-14 at 11:00 +0200, Thomas Gleixner wrote:
> > On Thu, 14 Aug 2008, Milan Plzik wrote:
> > >   I tried it just now, is performs a bit better than 2.6.26 (e.g. I
> > > don't get that "press any key unless nothing happens" states), even
> > > reports a bit more reasonable values of wakeups, but the system
> > > sometimes becomes rather slow (e.g. when playing video). I was not able
> > > to compile fglrx driver, so I had to change it to radeon one. And also,
> > > the number of wakeups reported is not very convincing, though, it
> > > changes from 300 to 600 (which is ~ two times the sum of wakeups)
> > > without any reason, and sometimes goes even higher.
> > > 
> > >   I tried to use nolapic_timer option, but it didn't help.
> > 
> > Can you please try "hpet=disable" on the kernel command line ?
> 
>   Looks like this has helped; after cold reboot hpet=disable seems to
> help the system to run properly (on 2.6.26 kernel). I wonder what could
> cause these problems. In the meanwhile I learned that this machine
> doesn't do proper cleanup during reboot -- it seems that state before
> reboot affects the state after reboot, so I should probably do some
> re-testing with cold reboot after each attempt. I guess I tried
> hpet=disable some time ago and after quick reboot it did not work
> properly.

  UPDATE: looks like it doesn't help always. I cold-booted twice, once
hpet=disable didn't help and the timing was messed up, the other time it
seemed to work just correctly. Maybe it's some race condition during
startup, but I was not able to find any substantial difference in kernel
messages emitted during boot, (just little changes like 2401.86 BogoMIPS
processor vs. 2401.88 and similar). 

> 
> > 
> > Thanks,
> > 	tglx
> 
>   Thank you,
> 	Milan

--
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/