Re: test13-pre5

From: David S. Miller (
Date: Thu Dec 28 2000 - 18:14:56 EST

   Date: Fri, 29 Dec 2000 00:17:21 +0100
   From: Andi Kleen <>

   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

David S. Miller
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
Please read the FAQ at

This archive was generated by hypermail 2b29 : Sun Dec 31 2000 - 21:00:11 EST