Commit c0d4ba05 authored by Mete Durlu's avatar Mete Durlu Committed by Vasily Gorbik
Browse files

s390/hiperdispatch: Add steal time averaging 



The measurements done by hiperdispatch can have sudden spikes and dips
during run time. To prevent these outliers effecting the decision making
process and causing adjustment overhead, use weighted average of the
steal time.

Acked-by: default avatarVasily Gorbik <gor@linux.ibm.com>
Co-developed-by: default avatarTobias Huschle <huschle@linux.ibm.com>
Signed-off-by: default avatarTobias Huschle <huschle@linux.ibm.com>
Signed-off-by: default avatarMete Durlu <meted@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
parent 6843d6d9

arch/s390/kernel/hiperdispatch.c

+10 −1
Original line number Diff line number Diff line
@@ -56,6 +56,7 @@ 
#define HD_DELAY_FACTOR			(4)

#define HD_DELAY_INTERVAL		(HZ / 4)

#define HD_STEAL_THRESHOLD		30

#define HD_STEAL_AVG_WEIGHT		16



static cpumask_t hd_vl_coremask;	/* Mask containing all vertical low COREs */

static cpumask_t hd_vmvl_cpumask;	/* Mask containing vertical medium and low CPUs */
@@ -136,6 +137,14 @@ int hd_enable_hiperdispatch(void) 
	return 1;

}



static unsigned long hd_steal_avg(unsigned long new)

{

	static unsigned long steal;



	steal = (steal * (HD_STEAL_AVG_WEIGHT - 1) + new) / HD_STEAL_AVG_WEIGHT;

	return steal;

}



static unsigned long hd_calculate_steal_percentage(void)

{

	unsigned long time_delta, steal_delta, steal, percentage;
@@ -185,7 +194,7 @@ static void hd_capacity_work_fn(struct work_struct *work) 
		mutex_unlock(&smp_cpu_state_mutex);

		return;

	}

	steal_percentage = hd_calculate_steal_percentage();

	steal_percentage = hd_steal_avg(hd_calculate_steal_percentage());

	if (steal_percentage < HD_STEAL_THRESHOLD)

		new_cores = hd_online_cores;

	else