From: Ralf Baechle <ralf@linux-mips.org>
To: David Daney <ddaney@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Subject: Re: [PATCH] MIPS: Handle removal of 'h' constraint in GCC 4.4
Date: Thu, 26 Feb 2009 16:58:00 +0000 [thread overview]
Message-ID: <20090226165800.GA31972@linux-mips.org> (raw)
In-Reply-To: <1235516662-24919-1-git-send-email-ddaney@caviumnetworks.com>
On Tue, Feb 24, 2009 at 03:04:22PM -0800, David Daney wrote:
> Due to the removal of the 'h' asm constraint in GCC-4.4, we need to
> adjust the computation in delay.h
It's time to take a step back and think over the whole thing once more.
Inlining __udelay can be problematic on some processors where the
execution performance of the delay loop will be different if the loop is
crossing a cacheline or not. That seems to particularly hit R10000
systems often. The number of the loop interations does the wrong tradeoff
between accuracy and the value range needed. The resulting overflows on a
HZ=128 4000 BogoMIPS machine are fantastic :-)
Time to reimplement udelay I'd say.
Ralf
next prev parent reply other threads:[~2009-02-26 16:58 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-24 23:04 [PATCH] MIPS: Handle removal of 'h' constraint in GCC 4.4 David Daney
2009-02-25 1:25 ` Maciej W. Rozycki
2009-02-26 16:58 ` Ralf Baechle [this message]
-- strict thread matches above, loose matches on Subject: below --
2008-12-18 2:24 David Daney
2008-12-19 0:46 ` Maciej W. Rozycki
2008-12-27 15:19 ` Richard Sandiford
2009-05-28 11:31 ` Florian Fainelli
2009-05-28 14:31 ` Wu Zhangjin
2009-05-28 15:43 ` David Daney
2009-05-28 16:00 ` Florian Fainelli
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