From: Abhijeet Kolekar <abhijeet.kolekar@xxxxxxxxx> Patch fixes the bug 1900 at http://www.intellinuxwireless.org/bugzilla/show_bug.cgi?id=1900 Issues: Throughput and success ratio calculations were not done properly. Number of retries were exceeding 16. Fix: Patch fixes above issues by doing window calculations inline with iwlwifi Patch adds sanity check to limit number of retries to 16. Signed-off-by: Abhijeet Kolekar <abhijeet.kolekar@xxxxxxxxx> Acked-by: Mohamed Abbas <mohamed.abbas@xxxxxxxxx> Signed-off-by: Reinette Chatre <reinette.chatre@xxxxxxxxx> --- drivers/net/wireless/iwlwifi/iwl-3945-rs.c | 127 +++++++++++++++++++--------- 1 files changed, 88 insertions(+), 39 deletions(-) diff --git a/drivers/net/wireless/iwlwifi/iwl-3945-rs.c b/drivers/net/wireless/iwlwifi/iwl-3945-rs.c index a266458..f65c308 100644 --- a/drivers/net/wireless/iwlwifi/iwl-3945-rs.c +++ b/drivers/net/wireless/iwlwifi/iwl-3945-rs.c @@ -127,6 +127,7 @@ static struct iwl3945_tpt_entry iwl3945_tpt_table_g[] = { #define IWL_RATE_MIN_FAILURE_TH 8 #define IWL_RATE_MIN_SUCCESS_TH 8 #define IWL_RATE_DECREASE_TH 1920 +#define IWL_RATE_RETRY_TH 15 static u8 iwl3945_get_rate_index_by_rssi(s32 rssi, enum ieee80211_band band) { @@ -298,37 +299,53 @@ static void iwl3945_collect_tx_data(struct iwl3945_rs_sta *rs_sta, } spin_lock_irqsave(&rs_sta->lock, flags); - while (retries--) { - /* If we have filled up the window then subtract one from the - * success counter if the high-bit is counting toward - * success */ - if (window->counter == IWL_RATE_MAX_WINDOW) { - if (window->data & (1ULL << (IWL_RATE_MAX_WINDOW - 1))) + /* + * Keep track of only the latest 62 tx frame attempts in this rate's + * history window; anything older isn't really relevant any more. + * If we have filled up the sliding window, drop the oldest attempt; + * if the oldest attempt (highest bit in bitmap) shows "success", + * subtract "1" from the success counter (this is the main reason + * we keep these bitmaps!). + * */ + while (retries > 0) { + if (window->counter >= IWL_RATE_MAX_WINDOW) { + + /* remove earliest */ + window->counter = IWL_RATE_MAX_WINDOW - 1; + + if (window->data & (1ULL << (IWL_RATE_MAX_WINDOW - 1))) { + window->data &= ~(1ULL << (IWL_RATE_MAX_WINDOW - 1)); window->success_counter--; - } else - window->counter++; + } + } - /* Slide the window to the left one bit */ - window->data = (window->data << 1); + /* Increment frames-attempted counter */ + window->counter++; - /* If this packet was a success then set the low bit high */ - if (success) { + /* Shift bitmap by one frame (throw away oldest history), + * OR in "1", and increment "success" if this + * frame was successful. */ + window->data <<= 1; + if (success > 0) { window->success_counter++; - window->data |= 1; + window->data |= 0x1; + success--; } - /* window->counter can't be 0 -- it is either >0 or - * IWL_RATE_MAX_WINDOW */ - window->success_ratio = 12800 * window->success_counter / - window->counter; - - /* Tag this window as having been updated */ - window->stamp = jiffies; - + retries--; } + /* Calculate current success ratio, avoid divide-by-0! */ + if (window->counter > 0) + window->success_ratio = 128 * (100 * window->success_counter) + / window->counter; + else + window->success_ratio = IWL_INVALID_VALUE; + fail_count = window->counter - window->success_counter; + + /* Calculate average throughput, if we have enough history. */ if ((fail_count >= IWL_RATE_MIN_FAILURE_TH) || (window->success_counter >= IWL_RATE_MIN_SUCCESS_TH)) window->average_tpt = ((window->success_ratio * @@ -336,6 +353,9 @@ static void iwl3945_collect_tx_data(struct iwl3945_rs_sta *rs_sta, else window->average_tpt = IWL_INVALID_VALUE; + /* Tag this window as having been updated */ + window->stamp = jiffies; + spin_unlock_irqrestore(&rs_sta->lock, flags); } @@ -468,7 +488,10 @@ static void rs_tx_status(void *priv_rate, struct ieee80211_supported_band *sband IWL_DEBUG_RATE(priv, "enter\n"); - retries = info->status.rates[0].count; + retries = info->status.rates[0].count - 1; + /* Sanity Check for retries */ + if (retries > IWL_RATE_RETRY_TH) + retries = IWL_RATE_RETRY_TH; first_index = sband->bitrates[info->status.rates[0].idx].hw_value; if ((first_index < 0) || (first_index >= IWL_RATE_COUNT_3945)) { @@ -724,7 +747,7 @@ static void rs_get_rate(void *priv_r, struct ieee80211_sta *sta, fail_count = window->counter - window->success_counter; - if (((fail_count <= IWL_RATE_MIN_FAILURE_TH) && + if (((fail_count < IWL_RATE_MIN_FAILURE_TH) && (window->success_counter < IWL_RATE_MIN_SUCCESS_TH))) { spin_unlock_irqrestore(&rs_sta->lock, flags); @@ -735,6 +758,9 @@ static void rs_get_rate(void *priv_r, struct ieee80211_sta *sta, window->counter, window->success_counter, rs_sta->expected_tpt ? "not " : ""); + + /* Can't calculate this yet; not enough history */ + window->average_tpt = IWL_INVALID_VALUE; goto out; } @@ -750,6 +776,7 @@ static void rs_get_rate(void *priv_r, struct ieee80211_sta *sta, if ((max_rate_idx != -1) && (max_rate_idx < high)) high = IWL_RATE_INVALID; + /* Collect Measured throughputs of adjacent rates */ if (low != IWL_RATE_INVALID) low_tpt = rs_sta->win[low].average_tpt; @@ -758,24 +785,43 @@ static void rs_get_rate(void *priv_r, struct ieee80211_sta *sta, spin_unlock_irqrestore(&rs_sta->lock, flags); - scale_action = 1; + scale_action = 0; + /* Low success ratio , need to drop the rate */ if ((window->success_ratio < IWL_RATE_DECREASE_TH) || !current_tpt) { IWL_DEBUG_RATE(priv, "decrease rate because of low success_ratio\n"); scale_action = -1; + + /* No throughput measured yet for adjacent rates, + * try increase */ } else if ((low_tpt == IWL_INVALID_VALUE) && - (high_tpt == IWL_INVALID_VALUE)) - scale_action = 1; - else if ((low_tpt != IWL_INVALID_VALUE) && + (high_tpt == IWL_INVALID_VALUE)) { + + if (high != IWL_RATE_INVALID && window->success_counter >= IWL_RATE_INCREASE_TH) + scale_action = 1; + else if (low != IWL_RATE_INVALID) + scale_action = -1; + + /* 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(priv, "No action -- low [%d] & high [%d] < " "current_tpt [%d]\n", low_tpt, high_tpt, current_tpt); scale_action = 0; + + /* At least one of the rates has better throughput */ } else { if (high_tpt != IWL_INVALID_VALUE) { - if (high_tpt > current_tpt) + + /* High rate has better throughput, Increase + * rate */ + if (high_tpt > current_tpt && + window->success_ratio >= IWL_RATE_INCREASE_TH) scale_action = 1; else { IWL_DEBUG_RATE(priv, @@ -787,29 +833,31 @@ static void rs_get_rate(void *priv_r, struct ieee80211_sta *sta, IWL_DEBUG_RATE(priv, "decrease rate because of low tpt\n"); scale_action = -1; - } else + } else if (window->success_counter >= IWL_RATE_INCREASE_TH) { + /* Lower rate has better + * throughput,decrease rate */ scale_action = 1; + } } } - if (scale_action == -1) { - if (window->success_ratio > IWL_SUCCESS_DOWN_TH) - scale_action = 0; - } else if (scale_action == 1) { - if (window->success_ratio < IWL_SUCCESS_UP_TH) { - IWL_DEBUG_RATE(priv, "No action -- success_ratio [%d] < " - "SUCCESS UP\n", window->success_ratio); - scale_action = 0; - } - } + /* Sanity check; asked for decrease, but success rate or throughput + * has been good at old rate. Don't change it. */ + if ((scale_action == -1) && (low != IWL_RATE_INVALID) && + ((window->success_ratio > IWL_RATE_HIGH_TH) || + (current_tpt > (100 * rs_sta->expected_tpt[low])))) + scale_action = 0; switch (scale_action) { case -1: + + /* Decrese rate */ if (low != IWL_RATE_INVALID) index = low; break; case 1: + /* Increase rate */ if (high != IWL_RATE_INVALID) index = high; @@ -817,6 +865,7 @@ static void rs_get_rate(void *priv_r, struct ieee80211_sta *sta, case 0: default: + /* No change */ break; } -- 1.5.6.3 -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
