| 1 | #include <stdlib.h>
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| 2 | #include <signal.h>
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| 3 | #include <unistd.h>
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| 4 | #include <linux/compiler.h>
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| 5 | #include "../tests.h"
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| 6 |
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| 7 | struct buf {
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| 8 | char data1;
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| 9 | char reserved[55];
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| 10 | char data2;
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| 11 | } __attribute__((aligned(64)));
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| 12 |
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| 13 |
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| 14 | static volatile struct buf workload_datasym_buf1 = {
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| 15 |
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| 16 | .reserved[0] = 1,
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| 17 | };
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| 18 |
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| 19 | static volatile sig_atomic_t done;
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| 20 |
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| 21 | static void sighandler(int sig __maybe_unused)
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| 22 | {
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| 23 | done = 1;
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| 24 | }
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| 25 |
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| 26 | static int datasym(int argc, const char **argv)
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| 27 | {
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| 28 | int sec = 1;
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| 29 |
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| 30 | if (argc > 0)
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| 31 | sec = atoi(argv[0]);
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| 32 |
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| 33 | signal(SIGINT, sighandler);
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| 34 | signal(SIGALRM, sighandler);
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| 35 | alarm(sec);
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| 36 |
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| 37 | while (!done) {
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| 38 | workload_datasym_buf1.data1++;
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| 39 | if (workload_datasym_buf1.data1 == 123) {
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| 40 | |
| 41 | * Add some 'noise' in the loop to work around errata
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| 42 | * 1694299 on Arm N1.
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| 43 | *
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| 44 | * Bias exists in SPE sampling which can cause the load
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| 45 | * and store instructions to be skipped entirely. This
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| 46 | * comes and goes randomly depending on the offset the
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| 47 | * linker places the datasym loop at in the Perf binary.
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| 48 | * With an extra branch in the middle of the loop that
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| 49 | * isn't always taken, the instruction stream is no
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| 50 | * longer a continuous repeating pattern that interacts
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| 51 | * badly with the bias.
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| 52 |
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| 53 | workload_datasym_buf1.data1++;
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| 54 | }
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| 55 | workload_datasym_buf1.data2 += workload_datasym_buf1.data1;
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| 56 | }
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| 57 | return 0;
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| 58 | }
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| 59 |
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| 60 | DEFINE_WORKLOAD(datasym);
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