lkml.org 
[lkml]   [2007]   [Mar]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [patch] cache pipe buf page address for non-highmem arch
On Fri, Mar 23, 2007 at 10:14:52AM +0000, Christoph Hellwig wrote:
> I think you're fixing the symptom here and not the cause. If calculating
> the virtual address of a page is so expensive on your setup it should
> define WANT_PAGE_VIRTUAL and we should always cache the virtual address
> in struct page. There's a lot more code, epecially in filesystems that's
> rather upset about a slow page_address.

Andi shot that down when I brought it up a while ago, as it does show
up in profiles for networking and other code paths. His argument is that
the loss of memory is excessive. Personally, I think the benefits of a
64 byte struct page on x86-64 outweigh the memory loss, as it means page
index to address translations are a simple shift.

-ben
--
"Time is of no importance, Mr. President, only life is important."
Don't Email: <zyntrop@kvack.org>.
-
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: 2007-03-24 02:43    [W:0.290 / U:0.044 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site