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/*
* Copyright (c) 2015, ARM Limited and Contributors. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of ARM nor the names of its contributors may be used
* to endorse or promote products derived from this software without specific
* prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* This file contains tests that measure the round trip latency of an SMC.
* The SMC calls used are simple ones (PSCI_VERSION and the Standard Service
* UID) that involve almost no handling on the EL3 firmware's side so that we
* come close to measuring the overhead of the SMC itself.
*/
#include <arch_helpers.h>
#include <debug.h>
#include <psci.h>
#include <std_svc.h>
#include <string.h>
#include <tftf_lib.h>
#define MIN(a, b) ((a) < (b) ? (a) : (b))
#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define ITERATIONS_CNT 1000
static unsigned long long raw_results[ITERATIONS_CNT];
/* Latency information in nano-seconds */
struct latency_info {
unsigned long long min;
unsigned long long max;
unsigned long long avg;
};
static inline unsigned long long cycles_to_ns(unsigned long long cycles)
{
unsigned long long freq = read_cntfrq_el0();
return (cycles * 1000000000) / freq;
}
/*
* Send the given SMC 'ITERATIONS_CNT' times, measure the time it takes to
* return back from the SMC call each time, and gather some statistics across
* the whole series.
*
* The statistics consist of:
* - minimum latency (i.e the shortest duration across the whole series);
* - maximum latency (i.e the longest duration across the whole series);
* - average latency.
*
* These statistics are stored in the latency_info structure whose address
* is passed as an argument.
*
* This function also prints some additional, intermediate information, like the
* number of cycles for each SMC and the average number of cycles for an SMC
* round trip.
*/
static void test_measure_smc_latency(const smc64_args *smc_args,
struct latency_info *latency)
{
unsigned long long cycles;
unsigned long long min_cycles;
unsigned long long max_cycles;
unsigned long long avg_cycles;
unsigned long long cycles_sum = 0;
min_cycles = UINT64_MAX;
max_cycles = 0;
memset(raw_results, 0, sizeof(raw_results));
for (unsigned int i = 0; i < ITERATIONS_CNT; ++i) {
cycles = read_cntpct_el0();
tftf_smc64(smc_args);
cycles = read_cntpct_el0() - cycles;
min_cycles = MIN(min_cycles, cycles);
max_cycles = MAX(max_cycles, cycles);
cycles_sum += cycles;
raw_results[i] = cycles;
}
avg_cycles = cycles_sum / ITERATIONS_CNT;
tftf_testcase_printf("Average number of cycles: %llu\n",
(unsigned long long) avg_cycles);
latency->min = cycles_to_ns(min_cycles);
latency->max = cycles_to_ns(max_cycles);
latency->avg = cycles_to_ns(avg_cycles);
NOTICE("Raw results:\n");
for (unsigned int i = 0; i < ITERATIONS_CNT; ++i) {
NOTICE("%llu cycles\t%llu ns\n",
raw_results[i], cycles_to_ns(raw_results[i]));
}
}
/*
* Measure the latency of the PSCI_VERSION SMC and print the result.
* This test always succeed.
*/
test_result_t smc_psci_version_latency(void)
{
struct latency_info latency;
smc64_args args = { PSCI_VERSION };
test_measure_smc_latency(&args, &latency);
tftf_testcase_printf(
"Average time: %llu ns (ranging from %llu to %llu)\n",
(unsigned long long) latency.avg,
(unsigned long long) latency.min,
(unsigned long long) latency.max);
return TEST_RESULT_SUCCESS;
}
/*
* Measure the latency of the Standard Service Call UID SMC and print the
* result.
* This test always succeed.
*/
test_result_t smc_std_svc_call_uid_latency(void)
{
struct latency_info latency;
smc64_args args = { SMC_STD_SVC_UID };
test_measure_smc_latency(&args, &latency);
tftf_testcase_printf(
"Average time: %llu ns (ranging from %llu to %llu)\n",
(unsigned long long) latency.avg,
(unsigned long long) latency.min,
(unsigned long long) latency.max);
return TEST_RESULT_SUCCESS;
}
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