[PATCH v1 1/2] perf expr: Make the evaluation of & and | logical and lazy

Ian Rogers
2023-05-04T20:21:35Z

Currently the & and | operators are only used in metric thresholds
like (from the tma_retiring metric):
tma_retiring > 0.7 | tma_heavy_operations > 0.1

Thresholds are always computed when present, but a lack events may
mean the threshold can't be computed. This happens with the option
--metric-no-threshold for say the metric tma_retiring on Tigerlake
model CPUs. To fully compute the threshold tma_heavy_operations is
needed and it needs the extra events of IDQ.MS_UOPS,
UOPS_DECODED.DEC0, cpu/UOPS_DECODED.DEC0,cmask=1/ and
IDQ.MITE_UOPS. So --metric-no-threshold is a useful option to reduce
the number of events needed and potentially multiplexing of events.

Rather than just fail threshold computations like this, we may know a
result from just the left or right-hand side. So, for tma_retiring if
its value is "> 0.7" we know it is over the threshold. This allows the
metric to have the threshold coloring, when possible, without all the
counters being programmed.

Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/tests/expr.c | 40 +++++++++++++++++++
tools/perf/util/expr.y | 86 +++++++++++++++++++++++++++++++++--------
2 files changed, 109 insertions(+), 17 deletions(-)

diff --git a/tools/perf/tests/expr.c b/tools/perf/tests/expr.c
index cbf0e0c74906..45c7fedb797a 100644
--- a/tools/perf/tests/expr.c
+++ b/tools/perf/tests/expr.c
@@ -184,6 +184,46 @@ static int test__expr(struct test_suite *t __maybe_unused, int subtest __maybe_u
NULL, ctx) == 0);
TEST_ASSERT_VAL("find ids", hashmap__size(ctx->ids) == 0);

+ /* The expression is a constant 0.0 without needing to evaluate EVENT1. */
+ expr__ctx_clear(ctx);
+ TEST_ASSERT_VAL("find ids",
+ expr__find_ids("0 & EVENT1 > 0", NULL, ctx) == 0);
+ TEST_ASSERT_VAL("find ids", hashmap__size(ctx->ids) == 0);
+ expr__ctx_clear(ctx);
+ TEST_ASSERT_VAL("find ids",
+ expr__find_ids("EVENT1 > 0 & 0", NULL, ctx) == 0);
+ TEST_ASSERT_VAL("find ids", hashmap__size(ctx->ids) == 0);
+ expr__ctx_clear(ctx);
+ TEST_ASSERT_VAL("find ids",
+ expr__find_ids("1 & EVENT1 > 0", NULL, ctx) == 0);
+ TEST_ASSERT_VAL("find ids", hashmap__size(ctx->ids) == 1);
+ TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "EVENT1", &val_ptr));
+ expr__ctx_clear(ctx);
+ TEST_ASSERT_VAL("find ids",
+ expr__find_ids("EVENT1 > 0 & 1", NULL, ctx) == 0);
+ TEST_ASSERT_VAL("find ids", hashmap__size(ctx->ids) == 1);
+ TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "EVENT1", &val_ptr));
+
+ /* The expression is a constant 1.0 without needing to evaluate EVENT1. */
+ expr__ctx_clear(ctx);
+ TEST_ASSERT_VAL("find ids",
+ expr__find_ids("1 | EVENT1 > 0", NULL, ctx) == 0);
+ TEST_ASSERT_VAL("find ids", hashmap__size(ctx->ids) == 0);
+ expr__ctx_clear(ctx);
+ TEST_ASSERT_VAL("find ids",
+ expr__find_ids("EVENT1 > 0 | 1", NULL, ctx) == 0);
+ TEST_ASSERT_VAL("find ids", hashmap__size(ctx->ids) == 0);
+ expr__ctx_clear(ctx);
+ TEST_ASSERT_VAL("find ids",
+ expr__find_ids("0 | EVENT1 > 0", NULL, ctx) == 0);
+ TEST_ASSERT_VAL("find ids", hashmap__size(ctx->ids) == 1);
+ TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "EVENT1", &val_ptr));
+ expr__ctx_clear(ctx);
+ TEST_ASSERT_VAL("find ids",
+ expr__find_ids("EVENT1 > 0 | 0", NULL, ctx) == 0);
+ TEST_ASSERT_VAL("find ids", hashmap__size(ctx->ids) == 1);
+ TEST_ASSERT_VAL("find ids", hashmap__find(ctx->ids, "EVENT1", &val_ptr));
+
/* Test toplogy constants appear well ordered. */
expr__ctx_clear(ctx);
TEST_ASSERT_VAL("#num_cpus", expr__parse(&num_cpus, ctx, "#num_cpus") == 0);
diff --git a/tools/perf/util/expr.y b/tools/perf/util/expr.y
index 250e444bf032..6b110f9f95c9 100644
--- a/tools/perf/util/expr.y
+++ b/tools/perf/util/expr.y
@@ -123,20 +123,6 @@ static struct ids handle_id(struct expr_parse_ctx *ctx, char *id,
* constant value using OP. Its invariant that there are no ids. If computing
* ids for non-constants union the set of IDs that must be computed.
*/
-#define BINARY_LONG_OP(RESULT, OP, LHS, RHS) \
- if (!compute_ids || (is_const(LHS.val) && is_const(RHS.val))) { \
- assert(LHS.ids == NULL); \
- assert(RHS.ids == NULL); \
- if (isnan(LHS.val) || isnan(RHS.val)) { \
- RESULT.val = NAN; \
- } else { \
- RESULT.val = (long)LHS.val OP (long)RHS.val; \
- } \
- RESULT.ids = NULL; \
- } else { \
- RESULT = union_expr(LHS, RHS); \
- }
-
#define BINARY_OP(RESULT, OP, LHS, RHS) \
if (!compute_ids || (is_const(LHS.val) && is_const(RHS.val))) { \
assert(LHS.ids == NULL); \
@@ -213,9 +199,75 @@ expr: NUMBER
}
| ID { $$ = handle_id(ctx, $1, compute_ids, /*source_count=*/false); }
| SOURCE_COUNT '(' ID ')' { $$ = handle_id(ctx, $3, compute_ids, /*source_count=*/true); }
-| expr '|' expr { BINARY_LONG_OP($$, |, $1, $3); }
-| expr '&' expr { BINARY_LONG_OP($$, &, $1, $3); }
-| expr '^' expr { BINARY_LONG_OP($$, ^, $1, $3); }
+| expr '|' expr
+{
+ if (is_const($1.val) && is_const($3.val)) {
+ assert($1.ids == NULL);
+ assert($3.ids == NULL);
+ $$.ids = NULL;
+ $$.val = (fpclassify($1.val) == FP_ZERO && fpclassify($3.val) == FP_ZERO) ? 0 : 1;
+ } else if (is_const($1.val)) {
+ assert($1.ids == NULL);
+ if (fpclassify($1.val) == FP_ZERO) {
+ $$ = $3;
+ } else {
+ $$.val = 1;
+ $$.ids = NULL;
+ ids__free($3.ids);
+ }
+ } else if (is_const($3.val)) {
+ assert($3.ids == NULL);
+ if (fpclassify($3.val) == FP_ZERO) {
+ $$ = $1;
+ } else {
+ $$.val = 1;
+ $$.ids = NULL;
+ ids__free($1.ids);
+ }
+ } else {
+ $$ = union_expr($1, $3);
+ }
+}
+| expr '&' expr
+{
+ if (is_const($1.val) && is_const($3.val)) {
+ assert($1.ids == NULL);
+ assert($3.ids == NULL);
+ $$.val = (fpclassify($1.val) != FP_ZERO && fpclassify($3.val) != FP_ZERO) ? 1 : 0;
+ $$.ids = NULL;
+ } else if (is_const($1.val)) {
+ assert($1.ids == NULL);
+ if (fpclassify($1.val) != FP_ZERO) {
+ $$ = $3;
+ } else {
+ $$.val = 0;
+ $$.ids = NULL;
+ ids__free($3.ids);
+ }
+ } else if (is_const($3.val)) {
+ assert($3.ids == NULL);
+ if (fpclassify($3.val) != FP_ZERO) {
+ $$ = $1;
+ } else {
+ $$.val = 0;
+ $$.ids = NULL;
+ ids__free($1.ids);
+ }
+ } else {
+ $$ = union_expr($1, $3);
+ }
+}
+| expr '^' expr
+{
+ if (is_const($1.val) && is_const($3.val)) {
+ assert($1.ids == NULL);
+ assert($3.ids == NULL);
+ $$.val = (fpclassify($1.val) == FP_ZERO) != (fpclassify($3.val) == FP_ZERO) ? 1 : 0;
+ $$.ids = NULL;
+ } else {
+ $$ = union_expr($1, $3);
+ }
+}
| expr '<' expr { BINARY_OP($$, <, $1, $3); }
| expr '>' expr { BINARY_OP($$, >, $1, $3); }
| expr '+' expr { BINARY_OP($$, +, $1, $3); }
--
2.40.1.521.gf1e218fcd8-goog