From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Csdncannon <csdncannon@gmail.com>
Cc: linuxppc-dev@ozlabs.org, Arnd Bergmann <arnd@arndb.de>
Subject: Re: Continual reading from the PowerPc time base register is not stable
Date: Thu, 25 Mar 2010 19:21:41 +1100 [thread overview]
Message-ID: <1269505301.8599.238.camel@pasglop> (raw)
In-Reply-To: <43c137a81003241941p84cba56y3e02e40cb22623e2@mail.gmail.com>
On Thu, 2010-03-25 at 10:41 +0800, Csdncannon wrote:
> In my program, the value of the 64-bit time base register is
> read out, and you will find the later value is even smaller than the
> earlier value from the log “log_timebase”. While the kernel depends on
> the accuracy of the timebase for the compensation of the lost PIT
> interrupt, the negative value between two continual timebase reading
> will bring to the jump of the jiffies. And this timebase problem will
> bring to the instability of the gettimeofday system call.
>
> Do you have any idea about this problem, thanks for your any
> advice. Attached is the code and log.
This is a concern, it should definitely not happen. What machine is
that ? is the code compiled 32-bit or 64-bit ? What kernel version ?
Arnd, any chance that could relate to the bug you've been chasing on
Cell ?
Cheers,
Ben.
>
> Thanks
>
> Gino
>
>
>
>
>
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev
next prev parent reply other threads:[~2010-03-25 8:21 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-25 2:41 Continual reading from the PowerPc time base register is not stable Csdncannon
2010-03-25 8:21 ` Benjamin Herrenschmidt [this message]
2010-03-25 10:05 ` Arnd Bergmann
2010-03-25 15:00 ` Csdncannon
2010-03-25 20:38 ` Benjamin Herrenschmidt
2010-03-26 1:11 ` Csdncannon
2010-03-26 1:22 ` Segher Boessenkool
2010-03-26 2:01 ` Csdncannon
2010-03-26 8:52 ` Segher Boessenkool
2010-03-26 9:01 ` Segher Boessenkool
2010-03-26 12:14 ` Csdncannon
2010-04-06 8:02 ` Csdncannon
2010-03-26 1:55 ` Benjamin Herrenschmidt
2010-03-26 2:04 ` Csdncannon
2010-03-25 22:00 ` Chris Friesen
2010-03-25 22:57 ` Benjamin Herrenschmidt
2010-03-25 23:37 ` Kumar Gala
2010-03-25 21:37 ` Segher Boessenkool
2010-04-10 3:14 ` Csdncannon
2010-04-22 0:44 ` Kim Phillips
2010-04-22 0:50 ` Benjamin Herrenschmidt
2010-04-22 23:27 ` Kim Phillips
2010-04-23 10:57 ` Csdncannon
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