Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=f8700df7c419781efb34696de7e7f49717f8ede7
Commit: f8700df7c419781efb34696de7e7f49717f8ede7
Parent: efe567fc8281661524ffa75477a7c4ca9b466c63
Author: Suresh Siddha <[EMAIL PROTECTED]>
AuthorDate: Thu Aug 23 15:18:02 2007 +0200
Committer: Ingo Molnar <[EMAIL PROTECTED]>
CommitDate: Thu Aug 23 15:18:02 2007 +0200
sched: fix broken SMT/MC optimizations
On a four package system with HT - HT load balancing optimizations were
broken. For example, if two tasks end up running on two logical threads
of one of the packages, scheduler is not able to pull one of the tasks
to a completely idle package.
In this scenario, for nice-0 tasks, imbalance calculated by scheduler
will be 512 and find_busiest_queue() will return 0 (as each cpu's load
is 1024 > imbalance and has only one task running).
Similarly MC scheduler optimizations also get fixed with this patch.
[ [EMAIL PROTECTED]: restored fair balancing by increasing the fuzz and
adding it back to the power decision, without the /2
factor. ]
Signed-off-by: Suresh Siddha <[EMAIL PROTECTED]>
Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
---
include/linux/sched.h | 2 +-
kernel/sched.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 1845b2e..ba78807 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -681,7 +681,7 @@ enum cpu_idle_type {
#define SCHED_LOAD_SHIFT 10
#define SCHED_LOAD_SCALE (1L << SCHED_LOAD_SHIFT)
-#define SCHED_LOAD_SCALE_FUZZ (SCHED_LOAD_SCALE >> 1)
+#define SCHED_LOAD_SCALE_FUZZ SCHED_LOAD_SCALE
#ifdef CONFIG_SMP
#define SD_LOAD_BALANCE 1 /* Do load balancing on this
domain. */
diff --git a/kernel/sched.c b/kernel/sched.c
index 5fecbbb..d96030d 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2517,7 +2517,7 @@ group_next:
* a think about bumping its value to force at least one task to be
* moved
*/
- if (*imbalance + SCHED_LOAD_SCALE_FUZZ < busiest_load_per_task/2) {
+ if (*imbalance + SCHED_LOAD_SCALE_FUZZ < busiest_load_per_task) {
unsigned long tmp, pwr_now, pwr_move;
unsigned int imbn;
-
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