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Message-ID: <87a5b0800811200946m4b58db6aoe91bfc45c38982bb@mail.gmail.com>
Date: Thu, 20 Nov 2008 17:46:04 +0000
From: "Will Newton" <will.newton@...il.com>
To: "Tim Bird" <tim.bird@...sony.com>
Cc: linux-kernel <linux-kernel@...r.kernel.org>,
"Andrew Morton" <akpm@...ux-foundation.org>
Subject: Re: [PATCH] init/main.c: Use ktime accessor function in initcall_debug code.
On Thu, Nov 20, 2008 at 5:39 PM, Tim Bird <tim.bird@...sony.com> wrote:
> Will Newton wrote:
>> The initcall_debug code access the tv64 member of ktime. This won't work
>> correctly for large deltas on platforms that don't use the scalar ktime
>> implementation.
>
> In principle I see no problem with this. But as a matter of
> practice it may be overkill.
Possibly, but it makes the code clearer I think.
> How big does the delta have to be for this to be a problem?
> And how much overhead does ktime_to_ns() add?
Deltas over a second will be incorrect. I have serial8250_init taking
8 seconds at the moment, so that isn't unheard of.
On scalar ktime architectures it should be zero, on others a multiply
and an add (it's an inline). I wouldn't call it a fast path though.
> -- Tim
>
> =============================
> Tim Bird
> Architecture Group Chair, CE Linux Forum
> Senior Staff Engineer, Sony Corporation of America
> =============================
>
>
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