From: Tim Bird <tim.bird@am.sony.com>
To: john stultz <johnstul@us.ibm.com>
Cc: linux kernel <linux-kernel@vger.kernel.org>
Subject: Re: [RFC][PATCH] new timeofday core subsystem (v. A2)
Date: Tue, 01 Feb 2005 14:06:07 -0800 [thread overview]
Message-ID: <41FFFD4F.9050900@am.sony.com> (raw)
In-Reply-To: <1106607089.30884.10.camel@cog.beaverton.ibm.com>
Minor spelling fix, and a question.
john stultz wrote:
> linux-2.6.11-rc2_timeofday-core_A2.patch
> ========================================
> diff -Nru a/drivers/Makefile b/drivers/Makefile
> --- a/drivers/Makefile 2005-01-24 13:30:06 -08:00
> +++ b/drivers/Makefile 2005-01-24 13:30:06 -08:00
...
> + * all systems. It has the same course resolution as
should be "coarse"
Do you replace get_cmos_time() - it doesn't look like it.
You use it in your patch here...
> diff -Nru a/arch/i386/kernel/time.c b/arch/i386/kernel/time.c
> --- a/arch/i386/kernel/time.c 2005-01-24 13:33:59 -08:00
> +++ b/arch/i386/kernel/time.c 2005-01-24 13:33:59 -08:00
...
> +/* arch specific timeofday hooks */
> +nsec_t read_persistent_clock(void)
> +{
> + return (nsec_t)get_cmos_time() * NSEC_PER_SEC;
> +}
> +
I didn't scan for all uses of read_persistent_clock, but
in my experience get_cmos_time() has a latency of up to
1 second on x86 because it synchronizes with the rollover
of the RTC seconds.
This comment in timeofday.c:timeofday_suspend_hook
worries me:
> + /* First off, save suspend start time
> + * then quickly read the time source.
> + * These two calls hopefully occur quickly
> + * because the difference will accumulate as
> + * time drift on resume.
> + */
> + suspend_start = read_persistent_clock();
Do you know if the sync problem is an issue here?
=============================
Tim Bird
Architecture Group Chair, CE Linux Forum
Senior Staff Engineer, Sony Electronics
=============================
next prev parent reply other threads:[~2005-02-01 22:06 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-01-24 22:51 [RFC][PATCH] new timeofday core subsystem (v. A2) john stultz
2005-01-24 22:52 ` [RFC][PATCH] new timeofday arch specific hooks " john stultz
2005-01-24 22:53 ` [RFC][PATCH] new timeofday arch specific timesources " john stultz
2005-01-24 23:29 ` Christoph Lameter
2005-01-25 0:04 ` john stultz
2005-01-25 2:28 ` [RFC][PATCH] new timeofday arch specific hooks " Benjamin Herrenschmidt
2005-01-25 23:09 ` john stultz
2005-01-25 23:53 ` Benjamin Herrenschmidt
2005-01-26 0:17 ` john stultz
2005-01-26 0:34 ` Christoph Lameter
2005-01-26 3:29 ` Benjamin Herrenschmidt
2005-01-26 16:51 ` Christoph Lameter
2005-01-26 3:14 ` Benjamin Herrenschmidt
2005-01-24 23:24 ` [RFC][PATCH] new timeofday core subsystem " Christoph Lameter
2005-01-25 0:03 ` john stultz
2005-01-25 0:08 ` Christoph Lameter
2005-01-25 0:33 ` john stultz
2005-01-25 1:54 ` Christoph Lameter
2005-01-25 7:50 ` Ulrich Windl
2005-01-25 12:25 ` Tim Schmielau
2005-01-25 7:41 ` Ulrich Windl
2005-01-25 8:17 ` Andi Kleen
2005-01-25 23:18 ` john stultz
2005-02-01 22:06 ` Tim Bird [this message]
2005-02-01 22:48 ` john stultz
2005-02-01 23:14 ` Nigel Cunningham
2005-02-01 23:32 ` john stultz
2005-02-02 0:04 ` Nigel Cunningham
2005-02-02 0:27 ` john stultz
2005-02-02 0:36 ` Nigel Cunningham
2005-02-01 23:53 ` Tim Bird
2005-02-02 0:19 ` john stultz
2005-02-02 1:48 ` Tim Bird
2005-02-02 2:00 ` john stultz
2005-02-02 2:23 ` Nigel Cunningham
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