From: akpm@linux-foundation.org
To: npiggin@suse.de, alan@lxorguk.ukuu.org.uk, mingo@elte.hu,
mm-commits@vger.kernel.org
Subject: - sched-avoid-div-in-rebalance_tick.patch removed from -mm tree
Date: Mon, 12 Feb 2007 14:47:22 -0800 [thread overview]
Message-ID: <200702122247.l1CMlMZ6013909@shell0.pdx.osdl.net> (raw)
The patch titled
sched: avoid div in rebalance_tick
has been removed from the -mm tree. Its filename was
sched-avoid-div-in-rebalance_tick.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: sched: avoid div in rebalance_tick
From: Nick Piggin <npiggin@suse.de>
Avoid expensive integer divide 3 times per CPU per tick.
A userspace test of this loop went from 26ns, down to 19ns on a G5; and
from 123ns down to 28ns on a P3.
(Also avoid a variable bit shift, as suggested by Alan. The effect
of this wasn't noticable on the CPUs I tested with).
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
kernel/sched.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff -puN kernel/sched.c~sched-avoid-div-in-rebalance_tick kernel/sched.c
--- a/kernel/sched.c~sched-avoid-div-in-rebalance_tick
+++ a/kernel/sched.c
@@ -2897,14 +2897,16 @@ static void active_load_balance(struct r
static void update_load(struct rq *this_rq)
{
unsigned long this_load;
- int i, scale;
+ unsigned int i, scale;
this_load = this_rq->raw_weighted_load;
/* Update our load: */
- for (i = 0, scale = 1; i < 3; i++, scale <<= 1) {
+ for (i = 0, scale = 1; i < 3; i++, scale += scale) {
unsigned long old_load, new_load;
+ /* scale is effectively 1 << i now, and >> i divides by scale */
+
old_load = this_rq->cpu_load[i];
new_load = this_load;
/*
@@ -2914,7 +2916,7 @@ static void update_load(struct rq *this_
*/
if (new_load > old_load)
new_load += scale-1;
- this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) / scale;
+ this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) >> i;
}
}
_
Patches currently in -mm which might be from npiggin@suse.de are
origin.patch
git-block.patch
fs-fix-__block_write_full_page-error-case-buffer-submission.patch
reply other threads:[~2007-02-12 22:47 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
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=200702122247.l1CMlMZ6013909@shell0.pdx.osdl.net \
--to=akpm@linux-foundation.org \
--cc=alan@lxorguk.ukuu.org.uk \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=mm-commits@vger.kernel.org \
--cc=npiggin@suse.de \
/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.