selftests: drv-net: Fix tolerance calculation in devlink_rate_tc_bw.py

Currently, tolerance is computed against the TC’s expected percentage,
making TC3 (20%) validation overly strict and TC4 (80%) overly loose.

Update BandwidthValidator to take a dict of shares and compute bounds
relative to the overall total, so that all shares are validated
consistently.

Signed-off-by: Carolina Jubran <cjubran@nvidia.com>
Reviewed-by: Cosmin Ratiu <cratiu@nvidia.com>
Reviewed-by: Nimrod Oren <noren@nvidia.com>
Link: https://patch.msgid.link/20251130091938.4109055-7-cjubran@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: cjubran

tools/testing/selftests/drivers/net/hw/devlink_rate_tc_bw.py

@@ -69,39 +69,35 @@
 
 class BandwidthValidator:
     """
-    Validates bandwidth totals and per-TC shares against expected values
-    with a tolerance.
+    Validates total bandwidth and individual shares with tolerance
+    relative to the overall total.
     """
 
-    def __init__(self):
+    def __init__(self, shares):
         self.tolerance_percent = 12
-        self.expected_total_gbps = 1.0
-        self.total_min_expected = self.min_expected(self.expected_total_gbps)
-        self.total_max_expected = self.max_expected(self.expected_total_gbps)
-        self.tc_expected_percent = {
-            3: 20.0,
-            4: 80.0,
-        }
+        self.expected_total = sum(shares.values())
+        self.bounds = {}
+
+        for name, exp in shares.items():
+            self.bounds[name] = (self.min_expected(exp), self.max_expected(exp))
 
     def min_expected(self, value):
         """Calculates the minimum acceptable value based on tolerance."""
-        return value - (value * self.tolerance_percent / 100)
+        return value - (self.expected_total * self.tolerance_percent / 100)
 
     def max_expected(self, value):
         """Calculates the maximum acceptable value based on tolerance."""
-        return value + (value * self.tolerance_percent / 100)
-
-    def bound(self, expected, value):
-        """Returns True if value is within expected tolerance."""
-        return self.min_expected(expected) <= value <= self.max_expected(expected)
+        return value + (self.expected_total * self.tolerance_percent / 100)
 
-    def tc_bandwidth_bound(self, value, tc_ix):
+    def bound(self, values):
         """
-        Returns True if the given bandwidth value is within tolerance
-        for the TC's expected bandwidth.
+        Return True if all given values fall within tolerance.
         """
-        expected = self.tc_expected_percent[tc_ix]
-        return self.bound(expected, value)
+        for name, value in values.items():
+            low, high = self.bounds[name]
+            if not low <= value <= high:
+                return False
+        return True
 
 
 def setup_vf(cfg, set_tc_mapping=True):
@@ -353,38 +349,26 @@ def verify_total_bandwidth(bw_data, validator):
     """
     total = bw_data['total_bw']
 
-    if validator.bound(validator.expected_total_gbps, total):
+    if validator.bound({"total": total}):
         return
 
-    if total < validator.total_min_expected:
+    low, high = validator.bounds["total"]
+
+    if total < low:
         raise KsftSkipEx(
             f"Total bandwidth {total:.2f} Gbps < minimum "
-            f"{validator.total_min_expected:.2f} Gbps; "
-            f"parent tx_max ({validator.expected_total_gbps:.1f} G) "
+            f"{low:.2f} Gbps; "
+            f"parent tx_max ({validator.expected_total:.1f} G) "
             f"not reached, cannot validate share"
         )
 
     raise KsftFailEx(
         f"Total bandwidth {total:.2f} Gbps exceeds allowed ceiling "
-        f"{validator.total_max_expected:.2f} Gbps "
-        f"(VF tx_max set to {validator.expected_total_gbps:.1f} G)"
+        f"{high:.2f} Gbps "
+        f"(VF tx_max set to {validator.expected_total:.1f} G)"
     )
 
 
-def check_bandwidth_distribution(bw_data, validator):
-    """
-    Checks whether the measured TC3 and TC4 bandwidth percentages
-    fall within their expected tolerance ranges.
-
-    Returns:
-        bool: True if both TC3 and TC4 percentages are within bounds.
-    """
-    tc3_valid = validator.tc_bandwidth_bound(bw_data['tc3_percentage'], 3)
-    tc4_valid = validator.tc_bandwidth_bound(bw_data['tc4_percentage'], 4)
-
-    return tc3_valid and tc4_valid
-
-
 def run_bandwidth_distribution_test(cfg, set_tc_mapping):
     """
     Runs parallel bandwidth measurements for both TCs and collects results.
@@ -395,9 +379,10 @@ def run_bandwidth_distribution_test(cfg, set_tc_mapping):
     test_name = "with TC mapping" if set_tc_mapping else "without TC mapping"
     print_bandwidth_results(bw_data, test_name)
 
-    verify_total_bandwidth(bw_data, cfg.bw_validator)
+    verify_total_bandwidth(bw_data, cfg.traffic_bw_validator)
 
-    return check_bandwidth_distribution(bw_data, cfg.bw_validator)
+    return cfg.tc_bw_validator.bound({"tc3": bw_data['tc3_percentage'],
+                                     "tc4": bw_data['tc4_percentage']})
 
 
 def test_no_tc_mapping_bandwidth(cfg):
@@ -441,7 +426,8 @@ def main() -> None:
         if not cfg.pci:
             raise KsftSkipEx("Could not get PCI address of the interface")
 
-        cfg.bw_validator = BandwidthValidator()
+        cfg.traffic_bw_validator = BandwidthValidator({"total": 1})
+        cfg.tc_bw_validator = BandwidthValidator({"tc3": 20, "tc4": 80})
 
         cases = [test_no_tc_mapping_bandwidth, test_tc_mapping_bandwidth]