86c5cf18db
The goal of this sample application is to measure the performance loss when a user thread has to go through a system call compared to a supervisor thread that calls the function directly. Signed-off-by: Nicolas Royer <nroyer@baylibre.com>
51 lines
1016 B
C
51 lines
1016 B
C
/*
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* Copyright (c) 2020 BayLibre, SAS
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <zephyr.h>
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#include <stdio.h>
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#include "main.h"
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/*
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* 0xB00 is CSR mcycle
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* 0xB02 is CSR minstret
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*/
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void supervisor_thread_function(void *p1, void *p2, void *p3)
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{
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register unsigned long cycle_before, cycle_count;
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register unsigned long inst_before, inst_count;
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printf("Supervisor thread started\n");
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while (1) {
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k_sleep(K_MSEC(2000));
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inst_before = csr_read(0xB02);
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cycle_before = csr_read(0xB00);
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k_current_get();
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cycle_count = csr_read(0xB00);
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inst_count = csr_read(0xB02);
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if (cycle_count > cycle_before) {
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cycle_count -= cycle_before;
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} else {
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cycle_count += 0xFFFFFFFF - cycle_before;
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}
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if (inst_count > inst_before) {
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inst_count -= inst_before;
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} else {
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inst_count += 0xFFFFFFFF - inst_before;
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}
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/* Remove CSR accesses to be more accurate */
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inst_count -= 3;
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printf("Supervisor thread:\t%8lu cycles\t%8lu instructions\n",
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cycle_count, inst_count);
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}
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}
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