Re: NS83820 2.6.0-test5 driver seems unstable on IA64

From: Peter Chubb <peter_at_chubb.wattle.id.au>
Date: 2003-09-23 20:40:05
>>>>> "David" == David S Miller <davem@redhat.com> writes:

David> On Mon, 22 Sep 2003 20:36:29 -0400 Benjamin LaHaise
David> <bcrl@kvack.org> wrote:

>> Denied.  Dave, please explain.

David> Why should I have anything to explain? :-)

David> The fact that ia64 is doing a printk for an unaligned kernel
David> load or store is what you should be asking questions about :)

How expensive is it to take the trap and do a fix up, compared to
making an aligned copy?  As it involves raising and handling a fault
disassembling the instruction that caused the fault, etc., I'd be
surprised if it's much less than 1000 cycles, even without the printk,
although I haven't measured it yet, and can't find enough info in the
architecture manuals to know what it is.

Even if it's only 500 cycles, you can copy and realign a large packet
in that time. 

--
Dr Peter Chubb  http://www.gelato.unsw.edu.au  peterc AT gelato.unsw.edu.au
You are lost in a maze of BitKeeper repositories,   all slightly different.
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Received on Tue Sep 23 06:41:13 2003

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