diff options
Diffstat (limited to 'tools/perf/tests/workloads/datasym.c')
| -rw-r--r-- | tools/perf/tests/workloads/datasym.c | 46 |
1 files changed, 41 insertions, 5 deletions
diff --git a/tools/perf/tests/workloads/datasym.c b/tools/perf/tests/workloads/datasym.c index ddd40bc63448..1d0b7d64e1ba 100644 --- a/tools/perf/tests/workloads/datasym.c +++ b/tools/perf/tests/workloads/datasym.c @@ -1,3 +1,6 @@ +#include <stdlib.h> +#include <signal.h> +#include <unistd.h> #include <linux/compiler.h> #include "../tests.h" @@ -7,16 +10,49 @@ typedef struct _buf { char data2; } buf __attribute__((aligned(64))); -static buf buf1 = { +/* volatile to try to avoid the compiler seeing reserved as unused. */ +static volatile buf workload_datasym_buf1 = { /* to have this in the data section */ .reserved[0] = 1, }; -static int datasym(int argc __maybe_unused, const char **argv __maybe_unused) +static volatile sig_atomic_t done; + +static void sighandler(int sig __maybe_unused) +{ + done = 1; +} + +static int datasym(int argc, const char **argv) { - for (;;) { - buf1.data1++; - buf1.data2 += buf1.data1; + int sec = 1; + + if (argc > 0) + sec = atoi(argv[0]); + + signal(SIGINT, sighandler); + signal(SIGALRM, sighandler); + alarm(sec); + + while (!done) { + workload_datasym_buf1.data1++; + if (workload_datasym_buf1.data1 == 123) { + /* + * Add some 'noise' in the loop to work around errata + * 1694299 on Arm N1. + * + * Bias exists in SPE sampling which can cause the load + * and store instructions to be skipped entirely. This + * comes and goes randomly depending on the offset the + * linker places the datasym loop at in the Perf binary. + * With an extra branch in the middle of the loop that + * isn't always taken, the instruction stream is no + * longer a continuous repeating pattern that interacts + * badly with the bias. + */ + workload_datasym_buf1.data1++; + } + workload_datasym_buf1.data2 += workload_datasym_buf1.data1; } return 0; } |