Re: [RFC][PATCH 1/6] kconfigurable resources core changes

From: Matthew Frost
Date: Thu May 18 2006 - 01:18:33 EST


Vivek Goyal wrote:
On Tue, May 09, 2006 at 02:33:48PM -0500, Kumar Gala wrote:
On May 5, 2006, at 12:28 PM, Vivek Goyal wrote:


o Core changes for Kconfigurable memory and IO resources. By default resources
are 64bit until chosen to be 32bit.

o Last time I posted the patches for 64bit memory resources but it raised
the concerns regarding code bloat on 32bit systems who use 32 bit
resources.

o This patch-set allows resources to be kconfigurable.

o I have done cross compilation on i386, x86_64, ppc, powerpc, sparc, sparc64
ia64 and alpha.

Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
---
[snip]

I didn't think the bloat was a big issue based on the numbers you reported. I'd still prefer to see us just move to a 64-bit resource on all systems.

I had also thought that bloat was not a big issue but Andrew thinks
otherwise. Here is the link to the thread.

http://marc.theaimsgroup.com/?l=linux-kernel&m=114626907106986&w=2
http://marc.theaimsgroup.com/?l=linux-kernel&m=114635425606186&w=2

In the latest patches, 64bit resources are default but one can force
these to be 32bit.


This may sound like a dumb question, but aside from code bloat, what are the performance issues involved in running 64-bit resources on 32-bit systems? AKA, does it kill us x86 users to not have this switch, and by what kind of margin? You can point if it's been said and I just haven't found it; I didn't see performance discussion in the last submission.

Thanks!
Matt

Thanks
Vivek
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