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From: Sergei Shtylyov <sshtylyov@ru.mvista.com>
To: Clem Taylor <clem.taylor@gmail.com>
Cc: Linux-MIPS <linux-mips@linux-mips.org>
Subject: Re: CONFIG_PRINTK_TIME and initial value for jiffies?
Date: Tue, 16 May 2006 01:11:55 +0400	[thread overview]
Message-ID: <4468EE9B.4000009@ru.mvista.com> (raw)
In-Reply-To: <ecb4efd10605151341l33f491f1ueca8a0ce609c989d@mail.gmail.com>

Hello.

Clem Taylor wrote:
> I just switched to 2.6.16.16 from 2.6.14 on a Au1550. I enabled
> CONFIG_PRINTK_TIME, and for some reason jiffies doesn't start out near
> zero like it does on x86. The first printk() always seems to have a
> time of 4284667.296000.

> jiffies_64 and wall_jiffies gets initialized to INITIAL_JIFFIES, but
> I'm not sure where jiffies is initialized. INITIAL_JIFFIES is -300*HZ
> (with some weird casting)

> The first line on the 2.6.16.16 Au1550 box is:
> [4294667.296000] Linux version 2.6.16.16 (ctaylor@gort) (gcc version
> 4.1.0) #4 Mon May 15 13:06:37 EDT 2006

    Well, this number looks a lot like -300 secs printed as unsigned --
given the fact that jiffies are unsigned, there's no surprise...
    My first guess is that TSC code used on x86 corrected jiffies_64 before 
they got used by sched_clock(). Probably a bogus guess because TSC should have 
been used by sched_clock() itsefl then...

MBR, Sergei

  reply	other threads:[~2006-05-15 21:13 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-05-15 20:41 CONFIG_PRINTK_TIME and initial value for jiffies? Clem Taylor
2006-05-15 21:11 ` Sergei Shtylyov [this message]
2006-05-15 21:35   ` Sergei Shtylyov
2006-05-16  6:03     ` Herbert Valerio Riedel
2006-05-16 12:35       ` Sergei Shtylyov
2006-05-22 16:27         ` Tim Bird

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