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[21/29] iwlwifi: mvm: rs: fix success ratio comparison in rs_get_best_rate

Message ID 1444055820-27506-21-git-send-email-luca@coelho.fi (mailing list archive)
State Accepted
Delegated to: Kalle Valo
Headers show

Commit Message

Luca Coelho Oct. 5, 2015, 2:36 p.m. UTC 
From: Eyal Shapira <eyal@wizery.com>

success_ratio is actually 128 * SR in percentage while
IWL_MVM_RS_SR_NO_DECREASE is 85%. Fix this by using RS_PERCENT().
This bug caused the if branch to be always executed. This in turn
led to always selecting a rate, following a column switch, in which
the expected throughput would exceed the best expected current throughput.
In some scenarios where the success ratio isn't >85% such a rate
could be too aggressive leading us to avoid the new column.
This has the potential of causing sub optimal performance.

Reported-by: Moshe Harel <moshe.harel@intel.com>
Signed-off-by: Eyal Shapira <eyalx.shapira@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
---
 drivers/net/wireless/iwlwifi/mvm/rs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
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Patch

diff --git a/drivers/net/wireless/iwlwifi/mvm/rs.c b/drivers/net/wireless/iwlwifi/mvm/rs.c
index 2bf2a08..435e1e4 100644
--- a/drivers/net/wireless/iwlwifi/mvm/rs.c
+++ b/drivers/net/wireless/iwlwifi/mvm/rs.c
@@ -1527,7 +1527,7 @@  static s32 rs_get_best_rate(struct iwl_mvm *mvm,
 	u32 target_tpt;
 	int rate_idx;
 
-	if (success_ratio > IWL_MVM_RS_SR_NO_DECREASE) {
+	if (success_ratio >= RS_PERCENT(IWL_MVM_RS_SR_NO_DECREASE)) {
 		target_tpt = 100 * expected_current_tpt;
 		IWL_DEBUG_RATE(mvm,
 			       "SR %d high. Find rate exceeding EXPECTED_CURRENT %d\n",
@@ -1535,7 +1535,7 @@  static s32 rs_get_best_rate(struct iwl_mvm *mvm,
 	} else {
 		target_tpt = lq_sta->last_tpt;
 		IWL_DEBUG_RATE(mvm,
-			       "SR %d not thag good. Find rate exceeding ACTUAL_TPT %d\n",
+			       "SR %d not that good. Find rate exceeding ACTUAL_TPT %d\n",
 			       success_ratio, target_tpt);
 	}