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sched: refine negative nice level granularity 

refine the granularity of negative nice level tasks: let them
reschedule more often to offset the effect of them consuming
their wait_runtime proportionately slower. (This makes nice-0
task scheduling smoother in the presence of negatively
reniced tasks.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar 2007-08-09 11:16:52 +02:00
parent a69edb5560
commit 7cff8cf61c
1 changed files with 11 additions and 7 deletions
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18
kernel/sched_fair.c
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@ -222,21 +222,25 @@ niced_granularity(struct sched_entity *curr, unsigned long granularity)
{
u64 tmp;
/*
* Negative nice levels get the same granularity as nice-0:
*/
if (likely(curr->load.weight >= NICE_0_LOAD))
if (likely(curr->load.weight == NICE_0_LOAD))
return granularity;
/*
* Positive nice level tasks get linearly finer
* Positive nice levels get the same granularity as nice-0:
*/
if (likely(curr->load.weight < NICE_0_LOAD)) {
tmp = curr->load.weight * (u64)granularity;
return (long) (tmp >> NICE_0_SHIFT);
}
/*
* Negative nice level tasks get linearly finer
* granularity:
*/
tmp = curr->load.weight * (u64)granularity;
tmp = curr->load.inv_weight * (u64)granularity;
/*
* It will always fit into 'long':
*/
return (long) (tmp >> NICE_0_SHIFT);
return (long) (tmp >> WMULT_SHIFT);
}
static inline void