4/13
Fix up a few small warts in the periodic multiprocessor rebalancing
code.
Signed-off-by: Nick Piggin <[EMAIL PROTECTED]>
Index: linux-2.6/kernel/sched.c
===================================================================
--- linux-2.6.orig/kernel/sched.c 2005-02-24 17:31:28.431609701 +1100
+++ linux-2.6/kernel/sched.c 2005-02-24 17:43:38.806447240 +1100
@@ -1830,13 +1830,12 @@
* by pulling tasks to us. Be careful of negative numbers as they'll
* appear as very large values with unsigned longs.
*/
- *imbalance = min(max_load - avg_load, avg_load - this_load);
-
/* How much load to actually move to equalise the imbalance */
- *imbalance = (*imbalance * min(busiest->cpu_power, this->cpu_power))
- / SCHED_LOAD_SCALE;
+ *imbalance = min((max_load - avg_load) * busiest->cpu_power,
+ (avg_load - this_load) * this->cpu_power)
+ / SCHED_LOAD_SCALE;
- if (*imbalance < SCHED_LOAD_SCALE - 1) {
+ if (*imbalance < SCHED_LOAD_SCALE) {
unsigned long pwr_now = 0, pwr_move = 0;
unsigned long tmp;
@@ -1862,14 +1861,16 @@
max_load - tmp);
/* Amount of load we'd add */
- tmp = SCHED_LOAD_SCALE*SCHED_LOAD_SCALE/this->cpu_power;
- if (max_load < tmp)
- tmp = max_load;
+ if (max_load*busiest->cpu_power <
+ SCHED_LOAD_SCALE*SCHED_LOAD_SCALE)
+ tmp = max_load*busiest->cpu_power/this->cpu_power;
+ else
+ tmp = SCHED_LOAD_SCALE*SCHED_LOAD_SCALE/this->cpu_power;
pwr_move += this->cpu_power*min(SCHED_LOAD_SCALE, this_load + tmp);
pwr_move /= SCHED_LOAD_SCALE;
- /* Move if we gain another 8th of a CPU worth of throughput */
- if (pwr_move < pwr_now + SCHED_LOAD_SCALE / 8)
+ /* Move if we gain throughput */
+ if (pwr_move <= pwr_now)
goto out_balanced;
*imbalance = 1;
@@ -1877,7 +1878,7 @@
}
/* Get rid of the scaling factor, rounding down as we divide */
- *imbalance = (*imbalance + 1) / SCHED_LOAD_SCALE;
+ *imbalance = *imbalance / SCHED_LOAD_SCALE;
return busiest;
