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Commit e53839eb authored by Eyal Shapira's avatar Eyal Shapira Committed by Emmanuel Grumbach
Browse files

iwlwifi: mvm: rs: fix and cleanup rs_get_rate_action 



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.

Cc: <stable@vger.kernel.org> [3.14]
Signed-off-by: default avatarEyal Shapira <eyalx.shapira@intel.com>
Signed-off-by: default avatarEmmanuel Grumbach <emmanuel.grumbach@intel.com>
parent 198266a3

drivers/net/wireless/iwlwifi/mvm/rs.c

+59 −68
Original line number Diff line number Diff line
@@ -1658,85 +1658,76 @@ static enum rs_action rs_get_rate_action(struct iwl_mvm *mvm, 
{

	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) {

			       "Decrease rate because of low SR\n");

		return RS_ACTION_DOWNSCALE;

	}



	if ((low_tpt == IWL_INVALID_VALUE) &&

	    (high_tpt == IWL_INVALID_VALUE) &&

	    (high != IWL_RATE_INVALID)) {

		IWL_DEBUG_RATE(mvm,

				       "Good SR and no high rate measurement. "

				       "Increase rate\n");

			action = RS_ACTION_UPSCALE;

		} else if (low != IWL_RATE_INVALID) {

			       "No data about high/low rates. Increase rate\n");

		return RS_ACTION_UPSCALE;

	}



	if ((high_tpt == IWL_INVALID_VALUE) &&

	    (high != IWL_RATE_INVALID) &&

	    (low_tpt != IWL_INVALID_VALUE) &&

	    (low_tpt < current_tpt)) {

		IWL_DEBUG_RATE(mvm,

				       "Remain in current 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;

	}



	/* 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) &&

	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;

			       "Both high and low are worse. Maintain rate\n");

		return 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) {

	if ((low_tpt != IWL_INVALID_VALUE) &&

	    (low_tpt > current_tpt)) {

		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 rate is better\n");

		action = RS_ACTION_DOWNSCALE;

		goto out;

	}



		/* Lower adjacent rate's throughput is measured */

		} else if (low_tpt != IWL_INVALID_VALUE) {

			/* Lower rate has better throughput */

			if (low_tpt > current_tpt) {

	if ((low_tpt == IWL_INVALID_VALUE) &&

	    (low != IWL_RATE_INVALID)) {

		IWL_DEBUG_RATE(mvm,

					       "Lower rate is better. "

					       "Decrease rate\n");

			       "No data about lower 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;

			}

		}

		goto out;

	}



	/* 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])))) {

	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,

			       "Sanity check failed. Maintain rate\n");

				       "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;

drivers/net/wireless/iwlwifi/mvm/rs.h

+1 −0
Original line number Diff line number Diff line
@@ -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)