lkml.org 
[lkml]   [2000]   [Dec]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: test13-pre5
   Date: Fri, 29 Dec 2000 00:17:21 +0100
From: Andi Kleen <ak@suse.de>

On Thu, Dec 28, 2000 at 02:54:52PM -0800, David S. Miller wrote:
> To make things like "page - mem_map" et al. use shifts instead of
> expensive multiplies...
I thought that is what ->index is for ?

It is for the page cache identity Andi... you know, page_hash(mapping, index)...

And the add/sub/shift expansion of a multiply/divide by constant even
in its' most optimal form is often not trivial, it is something on the
order of 7 instructions with waitq debugging enabled last time I
checked.

Later,
David S. Miller
davem@redhat.com
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 12:52    [from the cache]
©2003-2011 Jasper Spaans