lkml.org 
[lkml]   [2002]   [Jan]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] Remove 8 bytes from struct page on 64bit archs
On Mon, Jan 07, 2002 at 12:33:26AM +1100, Anton Blanchard wrote:
> For archs that need ->zone, merging it with ->flags sounds like a
> great idea. Id like to cram something into ->flags on 64 bit archs
> since its only a long due to bitop constraints. I had thought of
> stuffing ->count in the high word but now Im just getting silly
> since all non atomic accesses to ->flags would then have to be word
> ones.

At some point in the past, I wrote:
>> My i386 version, which makes ->virtual conditional on CONFIG_HIGHMEM as
>> well, is at:

On Mon, Jan 07, 2002 at 12:33:26AM +1100, Anton Blanchard wrote:
> Id like to do redo some profiling, on ppc64 we had page_address() doing
> pointer arithmetic (instead of page->virtual) and the compiler created
> an awful sequence of instructions in the acenic interrupt handler.
> A zero copy TCP benchmark made it rather obvious.

I'm not entirely surprised at this, CONFIG_HIGHMEM is probably just
not quite a strict enough criterion for eliminating ->virtual as it's
a time/space tradeoff that just happens to be bad on ppc64. Maybe we
should figure out some other criterion in addition to it.


Cheers,
Bill
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:18    [W:0.213 / U:0.008 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site