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Message-ID: <4743B0F4.8000302@redhat.com>
Date: Tue, 20 Nov 2007 23:15:48 -0500
From: Steven Rostedt <srostedt@...hat.com>
To: Gregory Haskins <ghaskins@...ell.com>
CC: LKML <linux-kernel@...r.kernel.org>,
Christoph Lameter <clameter@....com>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH] Fix optimized search
Gregory Haskins wrote:
> I spied a few more issues from http://lkml.org/lkml/2007/11/20/590.
>
> Patch is below..
Thanks, but I have one update...
>
> Regards,
> -Greg
>
> -----------------
>
> Include cpu 0 in the search, and eliminate the redundant cpu_set since
> the bit should already be set in the mask.
>
> Signed-off-by: Gregory Haskins <ghaskins@...ell.com>
> ---
>
> kernel/sched_rt.c | 7 +++----
> 1 files changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
> index 28feeff..fbf4fb1 100644
> --- a/kernel/sched_rt.c
> +++ b/kernel/sched_rt.c
> @@ -297,7 +297,7 @@ static DEFINE_PER_CPU(cpumask_t, local_cpu_mask);
> static int find_lowest_cpus(struct task_struct *task, cpumask_t *lowest_mask)
> {
> int lowest_prio = -1;
> - int lowest_cpu = 0;
> + int lowest_cpu = -1;
> int count = 0;
> int cpu;
>
> @@ -319,7 +319,7 @@ static int find_lowest_cpus(struct task_struct *task, cpumask_t *lowest_mask)
> * and the count==1 will cause the algorithm
> * to use the first bit found.
> */
> - if (lowest_cpu) {
> + if (lowest_cpu != -1) {
> cpus_clear(*lowest_mask);
> cpu_set(rq->cpu, *lowest_mask);
> }
> @@ -335,7 +335,6 @@ static int find_lowest_cpus(struct task_struct *task, cpumask_t *lowest_mask)
> lowest_cpu = cpu;
> count = 0;
> }
> - cpu_set(rq->cpu, *lowest_mask);
> count++;
> } else
> cpu_clear(cpu, *lowest_mask);
> @@ -346,7 +345,7 @@ static int find_lowest_cpus(struct task_struct *task, cpumask_t *lowest_mask)
> * runqueues that were of higher prio than
> * the lowest_prio.
> */
> - if (lowest_cpu) {
> + if (lowest_cpu != -1) {
We can change this to
if (lowest_cpu > 0) {
because if lowest_cpu == 0, we don't need to bother with clearing any bits.
I'll apply this next.
Thanks.
-- Steve
> /*
> * Perhaps we could add another cpumask op to
> * zero out bits. Like cpu_zero_bits(cpumask, nrbits);
>
-
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