s390/kernel/hiperdispatch.c

1 // SPDX-License-Identifier: GPL-2.0
11  * Dynamically calculates the optimum number of high capacity COREs
14  * During topology updates the CPU capacities are always re-adjusted.
18  * -> hiperdispatch's reoccuring work function reads CPU capacities to
19  *    determine high capacity CPU count.
20  * -> during a topology update hiperdispatch's adjustment function
30  * crosses the threshold value hiperdispatch falls back to giving high
33  * of them high capacity.
36  * performance. Comparing the throughput of;
37  * - single CORE, with N threads, running N tasks
38  * - N separate COREs running N tasks,
40  * performance. This performance difference is roughly ~30% (can change
72 static int hd_high_capacity_cores;	/* Current CORE count with high capacity */
73 static int hd_entitled_cores;		/* Total vertical high and medium CORE count */
77 static unsigned long hd_high_time;	/* Total time spent while all cpus have high capacity */
161 	upscaling_cores = hd_high_capacity_cores - hd_entitled_cores;  in hd_update_capacities()
169 		upscaling_cores--;  in hd_update_capacities()
202 	steal = (steal * (HD_STEAL_AVG_WEIGHT - 1) + new) / HD_STEAL_AVG_WEIGHT;  in hd_steal_avg()
222 	 * is 0 as vertical high CPUs shouldn't experience steal time.  in hd_calculate_steal_percentage()
229 		steal_delta = (steal - hd_previous_steal) * 100 / time_delta;  in hd_calculate_steal_percentage()
277 		.procname	= ctl->procname,  in hiperdispatch_ctl_handler()
322 		return -ERANGE;  in hd_steal_threshold_store()
348 		return -ERANGE;  in hd_delay_factor_store()
413 	if (sysfs_create_group(&dev->kobj, &hd_attr_group))  in hd_create_attributes()