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Re: [processor frequency]

To: "Kevin D. Kissell" <kevink@mips.com>
Subject: Re: [processor frequency]
From: Wolfgang Denk <wd@denx.de>
Date: Mon, 09 Jan 2006 22:23:39 +0100
Cc: "Sathesh Babu Edara" <satheshbabu.edara@analog.com>, linux-mips@linux-mips.org
In-reply-to: Your message of "Mon, 09 Jan 2006 10:00:48 +0100." <005a01c614fb$2fe76b00$10eca8c0@grendel>
Original-recipient: rfc822;linux-mips@linux-mips.org
Sender: linux-mips-bounce@linux-mips.org
In message <005a01c614fb$2fe76b00$10eca8c0@grendel> you wrote:
> There is no "ideal" value for a given processor frequency.
> The lower the value, the less interrupt processing overhead,
> but the slower the response time to events that are detected
> or serviced during clock interrupts. 1000 HZ *may* be a sensible
> value (I have my doubts, personally) for 2+ GHz PC processors, 
> but it's excessive (IMHO) for a 200MHz processor and unworkable 
> for a 20MHz CPU. I think that 100HZ is still a reasonable value
> for an embedded RISC CPU, but the "ideal" value is going to
> be a function of the application.

We did some tests of the performance impact of 100 vs. 1000 Hz  clock
frequency on low end systems (50 MHz PowerPC); for details please see
http://www.denx.de/wiki/view/Know/Clock100vs1000Hz

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de
Our missions are peaceful -- not for conquest.  When we do battle, it
is only because we have no choice.
        -- Kirk, "The Squire of Gothos", stardate 2124.5

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