Re: [PATCH] Fix optimized search

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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 <[email protected]>
---

 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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