Jonas Jelonek <jelonek.jonas@xxxxxxxxx> writes:
> Switching from legacy usage of ieee80211_get_tx_rates() lookup to direct
> rate table lookup in struct ieee80211_sta->rates.
>
> The current rate control API allows drivers to directly get rates from
> ieee80211_sta->rates. ath5k is currently one of the legacy drivers that
> perform translation/merge with the internal rate table via
> ieee80211_get_tx_rates provided by rate control API.
> For our upcoming changes to rate control API and the implementation of
> transmit power control, this patch changes the behaviour. The call to
> ieee80211_get_tx_rates and subsequent calls are also avoided. ath5k now
> directly reads rates from sta->rates into its internal rate table. Cause
> ath5k does not rely on the rate array in SKB->CB, this is not considered
> anymore except for the first entry (used for probing).
>
> Tested this on a PCEngines ALIX with CMP9-GP miniPCI wifi card (Atheros
> AR5213A). Generated traffic between AP and multiple STAs before and
> after applying the patch and simultaneously measured throughput and
> captured rc_stats. Comparison resulted in same rate selection and no
> performance loss between both runs.
Good that you explained how you tested this.
> @@ -753,8 +790,11 @@ ath5k_txbuf_setup(struct ath5k_hw *ah, struct ath5k_buf *bf,
> if (dma_mapping_error(ah->dev, bf->skbaddr))
> return -ENOSPC;
>
> - ieee80211_get_tx_rates(info->control.vif, (control) ? control->sta : NULL, skb, bf->rates,
> - ARRAY_SIZE(bf->rates));
> + if (!ath5k_merge_ratetbl((control) ? control->sta : NULL, bf, info)) {
> + ieee80211_get_tx_rates(info->control.vif,
> + (control) ? control->sta : NULL, skb, bf->rates,
> + ARRAY_SIZE(bf->rates));
> + }
I'm not really a fan of ? operator, so in the pending branch I changed
this to use a normal if statement. Please double check that I didn't
break anything.
https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/commit/?h=pending&id=9e7c92df342f884434ccc8635d2606c1d1b11ef9
diff --git a/drivers/net/wireless/ath/ath5k/base.c b/drivers/net/wireless/ath/ath5k/base.c
index 647b3b76495c..66d123f48085 100644
--- a/drivers/net/wireless/ath/ath5k/base.c
+++ b/drivers/net/wireless/ath/ath5k/base.c
@@ -774,6 +774,7 @@ ath5k_txbuf_setup(struct ath5k_hw *ah, struct ath5k_buf *bf,
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
unsigned int pktlen, flags, keyidx = AR5K_TXKEYIX_INVALID;
struct ieee80211_rate *rate;
+ struct ieee80211_sta *sta;
unsigned int mrr_rate[3], mrr_tries[3];
int i, ret;
u16 hw_rate;
@@ -790,10 +791,15 @@ ath5k_txbuf_setup(struct ath5k_hw *ah, struct ath5k_buf *bf,
if (dma_mapping_error(ah->dev, bf->skbaddr))
return -ENOSPC;
- if (!ath5k_merge_ratetbl((control) ? control->sta : NULL, bf, info)) {
+ if (control)
+ sta = control->sta;
+ else
+ sta = NULL;
+
+ if (!ath5k_merge_ratetbl(sta, bf, info)) {
ieee80211_get_tx_rates(info->control.vif,
- (control) ? control->sta : NULL, skb, bf->rates,
- ARRAY_SIZE(bf->rates));
+ sta, skb, bf->rates,
+ ARRAY_SIZE(bf->rates));
}
rate = ath5k_get_rate(ah->hw, info, bf, 0);
--
https://patchwork.kernel.org/project/linux-wireless/list/
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
