From: Andi Kleen <ak@suse.de>
To: Christoph Lameter <clameter@sgi.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Subject: Re: Some interesting observations when trying to optimize vmstat handling
Date: Fri, 9 Nov 2007 00:07:42 +0100 [thread overview]
Message-ID: <200711090007.43424.ak@suse.de> (raw)
In-Reply-To: <Pine.LNX.4.64.0711081141180.9694@schroedinger.engr.sgi.com>
> There is an interrupt enable overhead of 48 cycles that would be good to
> be able to eliminate (Kernel code usually moves counter increments into
> a neighboring interrupt disable section so that __ function can be used).
Replace the push flags ; popf with test $IFMASK,flags ; jz 1f; sti ; 1:
That will likely make it much faster (but also bigger)
The only problem is that there might be some code who relies on
restore_flags() restoring other flags that IF, but at least for interrupts
and local_irq_save/restore it should be fine to change.
-Andi
WARNING: multiple messages have this Message-ID (diff)
From: Andi Kleen <ak@suse.de>
To: Christoph Lameter <clameter@sgi.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Subject: Re: Some interesting observations when trying to optimize vmstat handling
Date: Fri, 9 Nov 2007 00:07:42 +0100 [thread overview]
Message-ID: <200711090007.43424.ak@suse.de> (raw)
In-Reply-To: <Pine.LNX.4.64.0711081141180.9694@schroedinger.engr.sgi.com>
> There is an interrupt enable overhead of 48 cycles that would be good to
> be able to eliminate (Kernel code usually moves counter increments into
> a neighboring interrupt disable section so that __ function can be used).
Replace the push flags ; popf with test $IFMASK,flags ; jz 1f; sti ; 1:
That will likely make it much faster (but also bigger)
The only problem is that there might be some code who relies on
restore_flags() restoring other flags that IF, but at least for interrupts
and local_irq_save/restore it should be fine to change.
-Andi
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2007-11-08 23:12 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-08 19:58 Some interesting observations when trying to optimize vmstat handling Christoph Lameter
2007-11-08 23:07 ` Andi Kleen [this message]
2007-11-08 23:07 ` Andi Kleen
2007-11-08 23:25 ` Christoph Lameter
2007-11-08 23:25 ` Christoph Lameter
2007-11-09 0:19 ` Jeremy Fitzhardinge
2007-11-09 0:19 ` Jeremy Fitzhardinge
2007-11-09 15:56 ` Andi Kleen
2007-11-09 15:56 ` Andi Kleen
2007-11-08 23:24 ` David Miller
2007-11-08 23:24 ` David Miller, 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=200711090007.43424.ak@suse.de \
--to=ak@suse.de \
--cc=clameter@sgi.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mathieu.desnoyers@polymtl.ca \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.