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Commit 3e5963bc authored by Michael Neuling's avatar Michael Neuling Committed by Rafael J. Wysocki
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cpufreq: powernv: Define per_cpu chip pointer to optimize hot-path 



Commit 96c4726f "cpufreq: powernv: Remove cpu_to_chip_id() from
hot-path" introduced a 'core_to_chip_map' array to cache the chip-ids
of all cores.

Replace this with a per-CPU variable that stores the pointer to the
chip-array. This removes the linear lookup and provides a neater and
simpler solution.

Signed-off-by: default avatarMichael Neuling <mikey@neuling.org>
Signed-off-by: default avatarShilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent ed72662a

drivers/cpufreq/powernv-cpufreq.c

+17 −33
Original line number Diff line number Diff line
@@ -44,7 +44,6 @@ 


static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1];

static bool rebooting, throttled, occ_reset;

static unsigned int *core_to_chip_map;



static const char * const throttle_reason[] = {

	"No throttling",
@@ -65,6 +64,7 @@ static struct chip { 
} *chips;



static int nr_chips;

static DEFINE_PER_CPU(struct chip *, chip_info);



/*

 * Note: The set of pstates consists of contiguous integers, the
@@ -324,34 +324,31 @@ static inline unsigned int get_nominal_index(void) 


static void powernv_cpufreq_throttle_check(void *data)

{

	struct chip *chip;

	unsigned int cpu = smp_processor_id();

	unsigned int chip_id = core_to_chip_map[cpu_core_index_of_thread(cpu)];

	unsigned long pmsr;

	int pmsr_pmax, i;

	int pmsr_pmax;



	pmsr = get_pmspr(SPRN_PMSR);



	for (i = 0; i < nr_chips; i++)

		if (chips[i].id == chip_id)

			break;

	chip = this_cpu_read(chip_info);



	/* Check for Pmax Capping */

	pmsr_pmax = (s8)PMSR_MAX(pmsr);

	if (pmsr_pmax != powernv_pstate_info.max) {

		if (chips[i].throttled)

		if (chip->throttled)

			goto next;

		chips[i].throttled = true;

		chip->throttled = true;

		if (pmsr_pmax < powernv_pstate_info.nominal)

			pr_warn_once("CPU %d on Chip %u has Pmax reduced below nominal frequency (%d < %d)\n",

				     cpu, chips[i].id, pmsr_pmax,

				     cpu, chip->id, pmsr_pmax,

				     powernv_pstate_info.nominal);

		trace_powernv_throttle(chips[i].id,

				      throttle_reason[chips[i].throttle_reason],

		trace_powernv_throttle(chip->id,

				      throttle_reason[chip->throttle_reason],

				      pmsr_pmax);

	} else if (chips[i].throttled) {

		chips[i].throttled = false;

		trace_powernv_throttle(chips[i].id,

				      throttle_reason[chips[i].throttle_reason],

	} else if (chip->throttled) {

		chip->throttled = false;

		trace_powernv_throttle(chip->id,

				      throttle_reason[chip->throttle_reason],

				      pmsr_pmax);

	}
@@ -558,47 +555,34 @@ static int init_chip_info(void) 
	unsigned int chip[256];

	unsigned int cpu, i;

	unsigned int prev_chip_id = UINT_MAX;

	cpumask_t cpu_mask;

	int ret = -ENOMEM;



	core_to_chip_map = kcalloc(cpu_nr_cores(), sizeof(unsigned int),

				   GFP_KERNEL);

	if (!core_to_chip_map)

		goto out;



	cpumask_copy(&cpu_mask, cpu_possible_mask);

	for_each_cpu(cpu, &cpu_mask) {

	for_each_possible_cpu(cpu) {

		unsigned int id = cpu_to_chip_id(cpu);



		if (prev_chip_id != id) {

			prev_chip_id = id;

			chip[nr_chips++] = id;

		}

		core_to_chip_map[cpu_core_index_of_thread(cpu)] = id;

		cpumask_andnot(&cpu_mask, &cpu_mask, cpu_sibling_mask(cpu));

	}



	chips = kcalloc(nr_chips, sizeof(struct chip), GFP_KERNEL);

	if (!chips)

		goto free_chip_map;

		return -ENOMEM;



	for (i = 0; i < nr_chips; i++) {

		chips[i].id = chip[i];

		cpumask_copy(&chips[i].mask, cpumask_of_node(chip[i]));

		INIT_WORK(&chips[i].throttle, powernv_cpufreq_work_fn);

		for_each_cpu(cpu, &chips[i].mask)

			per_cpu(chip_info, cpu) =  &chips[i];

	}



	return 0;

free_chip_map:

	kfree(core_to_chip_map);

out:

	return ret;

}



static inline void clean_chip_info(void)

{

	kfree(chips);

	kfree(core_to_chip_map);

}



static inline void unregister_all_notifiers(void)