From: Andi Kleen <ak@suse.de>
To: Christoph Lameter <clameter@sgi.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Prezeroing V2 [0/3]: Why and When it works
Date: 23 Dec 2004 21:27:38 +0100 [thread overview]
Message-ID: <p73ekhgzrnp.fsf@verdi.suse.de> (raw)
In-Reply-To: <Pine.LNX.4.58.0412231119540.31791@schroedinger.engr.sgi.com.suse.lists.linux.kernel>
Christoph Lameter <clameter@sgi.com> writes:
> and why other approaches have not worked.
> o Instead of zero_page(p,order) extend clear_page to take second argument
> o Update all architectures to accept second argument for clear_pages
Sorry if there was a miscommunication, but ...
> 1. Aggregating zeroing operations to only apply to pages of higher order,
> which results in many pages that will later become order 0 to be
> zeroed in one go. For that purpose the existing clear_page function is
> extended and made to take an additional argument specifying the order of
> the page to be cleared.
But if you do that you should really use a separate function that
can use cache bypassing stores.
Normal clear_page cannot use that because it would be a loss
when the data is soon used.
So the two changes don't really make sense.
Also I must say I'm still suspicious regarding your heuristic
to trigger gang faulting - with bad luck it could lead to a lot
more memory usage to specific applications that do very sparse
usage of memory.
There should be at least an madvise flag to turn it off and a sysctl
and it would be better to trigger only on a longer sequence of
consecutive faulted pages.
> 2. Hardware support for offloading zeroing from the cpu. This avoids
> the invalidation of the cpu caches by extensive zeroing operations.
>
> The result is a significant increase of the page fault performance even for
> single threaded applications:
[...]
How about some numbers on i386?
-Andi
next prev parent reply other threads:[~2004-12-23 20:27 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <B8E391BBE9FE384DAA4C5C003888BE6F02900FBD@scsmsx401.amr.corp.intel.com.suse.lists.linux.kernel>
[not found] ` <41C20E3E.3070209@yahoo.com.au.suse.lists.linux.kernel>
[not found] ` <Pine.LNX.4.58.0412211154100.1313@schroedinger.engr.sgi.com.suse.lists.linux.kernel>
[not found] ` <Pine.LNX.4.58.0412211155340.1313@schroedinger.engr.sgi.com.suse.lists.linux.kernel>
2004-12-21 22:40 ` Increase page fault rate by prezeroing V1 [1/3]: Introduce __GFP_ZERO Andi Kleen
2004-12-21 22:54 ` Christoph Lameter
2004-12-22 10:53 ` Andi Kleen
2004-12-22 19:54 ` Christoph Lameter
[not found] ` <Pine.LNX.4.58.0412231119540.31791@schroedinger.engr.sgi.com.suse.lists.linux.kernel>
2004-12-23 20:27 ` Andi Kleen [this message]
2004-12-23 21:02 ` Prezeroing V2 [0/3]: Why and When it works Christoph Lameter
[not found] <B8E391BBE9FE384DAA4C5C003888BE6F02900FBD@scsmsx401.amr.corp.intel.com>
[not found] ` <41C20E3E.3070209@yahoo.com.au>
2004-12-21 19:55 ` Increase page fault rate by prezeroing V1 [0/3]: Overview Christoph Lameter
2004-12-23 19:29 ` Prezeroing V2 [0/3]: Why and When it works Christoph Lameter
2004-12-23 19:49 ` Arjan van de Ven
2004-12-23 20:57 ` Matt Mackall
2004-12-23 21:01 ` Paul Mackerras
2004-12-23 21:11 ` Paul Mackerras
2004-12-23 21:37 ` Andrew Morton
2004-12-23 23:00 ` Paul Mackerras
2004-12-23 21:48 ` Linus Torvalds
2004-12-23 22:34 ` Zwane Mwaikambo
2004-12-24 9:14 ` Arjan van de Ven
2004-12-24 18:21 ` Linus Torvalds
2004-12-24 18:57 ` Arjan van de Ven
2004-12-27 22:50 ` David S. Miller
2004-12-28 11:53 ` Marcelo Tosatti
2004-12-24 16:17 ` Christoph Lameter
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=p73ekhgzrnp.fsf@verdi.suse.de \
--to=ak@suse.de \
--cc=clameter@sgi.com \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).