diff options
Diffstat (limited to 'tools/perf/tests/workloads/datasym.c')
| -rw-r--r-- | tools/perf/tests/workloads/datasym.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/tools/perf/tests/workloads/datasym.c b/tools/perf/tests/workloads/datasym.c index ddd40bc63448ae..8e08fc75a973e5 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; |