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-rw-r--r--tools/perf/tests/workloads/datasym.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/tools/perf/tests/workloads/datasym.c b/tools/perf/tests/workloads/datasym.c
index ddd40bc634..8e08fc75a9 100644
--- a/tools/perf/tests/workloads/datasym.c
+++ b/tools/perf/tests/workloads/datasym.c
@@ -16,6 +16,22 @@ static int datasym(int argc __maybe_unused, const char **argv __maybe_unused)
{
for (;;) {
buf1.data1++;
+ if (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.
+ */
+ buf1.data1++;
+ }
buf1.data2 += buf1.data1;
}
return 0;