[PATCH 3.14 024/228] iwlwifi: mvm: rs: fix and cleanup rs_get_rate_action

Greg Kroah-Hartman
2014-06-04T23:21:15Z

From: Eyal Shapira <eyal@wizery.com>

commit e53839eb9882c99d3781eab0fe1b2d4369a6a2cc upstream.

Change the down/upscale decision logic a bit to be based
on different success ratio thresholds. This fixes the implementation
compared to the rate scale algorithm which was planned to yield
optimal results. Also fix a case where a lower rate wasn't explored
despite being a potential for better throughput.
While at it rewrite rs_get_rate_action to be more clear and clean.

Signed-off-by: Eyal Shapira <eyalx.shapira@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/wireless/iwlwifi/mvm/rs.c | 135 +++++++++++++++-------------------
drivers/net/wireless/iwlwifi/mvm/rs.h | 1
2 files changed, 64 insertions(+), 72 deletions(-)

--- a/drivers/net/wireless/iwlwifi/mvm/rs.c
+++ b/drivers/net/wireless/iwlwifi/mvm/rs.c
@@ -1644,85 +1644,76 @@ static enum rs_action rs_get_rate_action
{
enum rs_action action = RS_ACTION_STAY;

- /* Too many failures, decrease rate */
if ((sr <= RS_SR_FORCE_DECREASE) || (current_tpt == 0)) {
IWL_DEBUG_RATE(mvm,
- "decrease rate because of low SR\n");
- action = RS_ACTION_DOWNSCALE;
- /* No throughput measured yet for adjacent rates; try increase. */
- } else if ((low_tpt == IWL_INVALID_VALUE) &&
- (high_tpt == IWL_INVALID_VALUE)) {
- if (high != IWL_RATE_INVALID && sr >= IWL_RATE_INCREASE_TH) {
- IWL_DEBUG_RATE(mvm,
- "Good SR and no high rate measurement. "
- "Increase rate\n");
- action = RS_ACTION_UPSCALE;
- } else if (low != IWL_RATE_INVALID) {
- IWL_DEBUG_RATE(mvm,
- "Remain in current rate\n");
- action = RS_ACTION_STAY;
- }
+ "Decrease rate because of low SR\n");
+ return RS_ACTION_DOWNSCALE;
}

- /* Both adjacent throughputs are measured, but neither one has better
- * throughput; we're using the best rate, don't change it!
- */
- else if ((low_tpt != IWL_INVALID_VALUE) &&
- (high_tpt != IWL_INVALID_VALUE) &&
- (low_tpt < current_tpt) &&
- (high_tpt < current_tpt)) {
- IWL_DEBUG_RATE(mvm,
- "Both high and low are worse. "
- "Maintain rate\n");
- action = RS_ACTION_STAY;
- }
-
- /* At least one adjacent rate's throughput is measured,
- * and may have better performance.
- */
- else {
- /* Higher adjacent rate's throughput is measured */
- if (high_tpt != IWL_INVALID_VALUE) {
- /* Higher rate has better throughput */
- if (high_tpt > current_tpt &&
- sr >= IWL_RATE_INCREASE_TH) {
- IWL_DEBUG_RATE(mvm,
- "Higher rate is better and good "
- "SR. Increate rate\n");
- action = RS_ACTION_UPSCALE;
- } else {
- IWL_DEBUG_RATE(mvm,
- "Higher rate isn't better OR "
- "no good SR. Maintain rate\n");
- action = RS_ACTION_STAY;
- }
-
- /* Lower adjacent rate's throughput is measured */
- } else if (low_tpt != IWL_INVALID_VALUE) {
- /* Lower rate has better throughput */
- if (low_tpt > current_tpt) {
- IWL_DEBUG_RATE(mvm,
- "Lower rate is better. "
- "Decrease rate\n");
- action = RS_ACTION_DOWNSCALE;
- } else if (sr >= IWL_RATE_INCREASE_TH) {
- IWL_DEBUG_RATE(mvm,
- "Lower rate isn't better and "
- "good SR. Increase rate\n");
- action = RS_ACTION_UPSCALE;
- }
- }
+ if ((low_tpt == IWL_INVALID_VALUE) &&
+ (high_tpt == IWL_INVALID_VALUE) &&
+ (high != IWL_RATE_INVALID)) {
+ IWL_DEBUG_RATE(mvm,
+ "No data about high/low rates. Increase rate\n");
+ return RS_ACTION_UPSCALE;
}

- /* Sanity check; asked for decrease, but success rate or throughput
- * has been good at old rate. Don't change it.
- */
- if ((action == RS_ACTION_DOWNSCALE) && (low != IWL_RATE_INVALID) &&
- ((sr > IWL_RATE_HIGH_TH) ||
- (current_tpt > (100 * tbl->expected_tpt[low])))) {
+ if ((high_tpt == IWL_INVALID_VALUE) &&
+ (high != IWL_RATE_INVALID) &&
+ (low_tpt != IWL_INVALID_VALUE) &&
+ (low_tpt < current_tpt)) {
IWL_DEBUG_RATE(mvm,
- "Sanity check failed. Maintain rate\n");
- action = RS_ACTION_STAY;
+ "No data about high rate and low rate is worse. Increase rate\n");
+ return RS_ACTION_UPSCALE;
+ }
+
+ if ((high_tpt != IWL_INVALID_VALUE) &&
+ (high_tpt > current_tpt)) {
+ IWL_DEBUG_RATE(mvm,
+ "Higher rate is better. Increate rate\n");
+ return RS_ACTION_UPSCALE;
+ }
+
+ if ((low_tpt != IWL_INVALID_VALUE) &&
+ (high_tpt != IWL_INVALID_VALUE) &&
+ (low_tpt < current_tpt) &&
+ (high_tpt < current_tpt)) {
+ IWL_DEBUG_RATE(mvm,
+ "Both high and low are worse. Maintain rate\n");
+ return RS_ACTION_STAY;
+ }
+
+ if ((low_tpt != IWL_INVALID_VALUE) &&
+ (low_tpt > current_tpt)) {
+ IWL_DEBUG_RATE(mvm,
+ "Lower rate is better\n");
+ action = RS_ACTION_DOWNSCALE;
+ goto out;
+ }
+
+ if ((low_tpt == IWL_INVALID_VALUE) &&
+ (low != IWL_RATE_INVALID)) {
+ IWL_DEBUG_RATE(mvm,
+ "No data about lower rate\n");
+ action = RS_ACTION_DOWNSCALE;
+ goto out;
+ }
+
+ IWL_DEBUG_RATE(mvm, "Maintain rate\n");
+
+out:
+ if ((action == RS_ACTION_DOWNSCALE) && (low != IWL_RATE_INVALID)) {
+ if (sr >= RS_SR_NO_DECREASE) {
+ IWL_DEBUG_RATE(mvm,
+ "SR is above NO DECREASE. Avoid downscale\n");
+ action = RS_ACTION_STAY;
+ } else if (current_tpt > (100 * tbl->expected_tpt[low])) {
+ IWL_DEBUG_RATE(mvm,
+ "Current TPT is higher than max expected in low rate. Avoid downscale\n");
+ action = RS_ACTION_STAY;
+ } else {
+ IWL_DEBUG_RATE(mvm, "Decrease rate\n");
+ }
}

return action;
--- a/drivers/net/wireless/iwlwifi/mvm/rs.h
+++ b/drivers/net/wireless/iwlwifi/mvm/rs.h
@@ -156,6 +156,7 @@ enum {
#define IWL_RATE_HIGH_TH 10880 /* 85% */
#define IWL_RATE_INCREASE_TH 6400 /* 50% */
#define RS_SR_FORCE_DECREASE 1920 /* 15% */
+#define RS_SR_NO_DECREASE 10880 /* 85% */

#define LINK_QUAL_AGG_TIME_LIMIT_DEF (4000) /* 4 milliseconds */
#define LINK_QUAL_AGG_TIME_LIMIT_MAX (8000)