From: Andrew Morton <akpm@osdl.org>
To: george@mvista.com
Cc: johnstul@us.ibm.com, herbert@13thfloor.at, linux-kernel@vger.kernel.org
Subject: Re: do_posix_clock_monotonic_gettime() returns negative nsec
Date: Fri, 3 Dec 2004 00:56:46 -0800 [thread overview]
Message-ID: <20041203005646.077e2e34.akpm@osdl.org> (raw)
In-Reply-To: <41B02749.70900@mvista.com>
George Anzinger <george@mvista.com> wrote:
>
> > George: You have any comment?
>
> Two, in fact. First, the result here is the sum of wall_to_monotonic and
> getnstimeofday(). If nsec < 0, one or more of these must be also. Both of
> these values are SUPPOSED to be normalized.
As Herbert points out, hpet_time_init() and time_init() and who knows what
else do:
wall_to_monotonic.tv_sec = -xtime.tv_sec;
xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
wall_to_monotonic.tv_nsec = -xtime.tv_nsec;
And this:
* The current time
* wall_to_monotonic is what we need to add to xtime (or xtime corrected
* for sub jiffie times) to get to monotonic time. Monotonic is pegged at zero
* at zero at system boot time, so wall_to_monotonic will be negative,
* however, we will ALWAYS keep the tv_nsec part positive so we can use
* the usual normalization.
So I assume the bug is that time_init() is failing to normalise
wall_to_monotonic?
next prev parent reply other threads:[~2004-12-03 8:57 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-03 2:03 do_posix_clock_monotonic_gettime() returns negative nsec Herbert Poetzl
2004-12-03 3:00 ` john stultz
2004-12-03 8:43 ` George Anzinger
2004-12-03 8:56 ` Andrew Morton [this message]
2004-12-03 3:08 ` Andrew Morton
2004-12-03 3:20 ` Herbert Poetzl
2004-12-03 8:53 ` George Anzinger
2004-12-03 17:22 ` Herbert Poetzl
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