remove_interactive_credit

remove_interactive_credit

Please include in -mm for a few weeks testing.

Special casing tasks by interactive credit was helpful for preventing fully cpu bound tasks from easily rising to interactive status.

However it did not select out tasks that had periods of being fully cpu bound and then sleeping while waiting on pipes, signals etc. This led to a more disproportionate share of cpu time.

Backing this out will no longer special case only fully cpu bound tasks, and prevents the variable behaviour that occurs at startup before tasks declare themseleves interactive or not, and speeds up application startup slightly under certain circumstances. It does cost in interactivity slightly as load rises but it is worth it for the fairness gains.

Index: linux-2.6.10-rc1-mm3/include/linux/sched.h
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@@ -527,7 +527,6 @@ struct task_struct {
 	prio_array_t *array;
 
 	unsigned long sleep_avg;
-	long interactive_credit;
 	unsigned long long timestamp, last_ran;
 	int activated;