ath10k: replenish HTT RX buffers in a tasklet
This starves FW RX ring buffer in case of excessive RX. This prevents from CPU being overwhelmed by RX indications/completions by naturally forbiddin FW to submit more RX. This fixes RX starvation on slow machines when under heavy RX traffic. kvalo: remove extra newline Signed-off-by: Michal Kazior <michal.kazior@tieto.com> Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
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@ -19,6 +19,7 @@
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#define _HTT_H_
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#include <linux/bug.h>
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#include <linux/interrupt.h>
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#include "htc.h"
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#include "rx_desc.h"
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@ -1268,6 +1269,7 @@ struct ath10k_htt {
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/* set if host-fw communication goes haywire
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* used to avoid further failures */
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bool rx_confused;
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struct tasklet_struct rx_replenish_task;
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};
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#define RX_HTT_HDR_STATUS_LEN 64
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@ -1308,6 +1310,10 @@ struct htt_rx_desc {
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#define HTT_RX_BUF_SIZE 1920
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#define HTT_RX_MSDU_SIZE (HTT_RX_BUF_SIZE - (int)sizeof(struct htt_rx_desc))
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/* Refill a bunch of RX buffers for each refill round so that FW/HW can handle
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* aggregated traffic more nicely. */
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#define ATH10K_HTT_MAX_NUM_REFILL 16
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/*
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* DMA_MAP expects the buffer to be an integral number of cache lines.
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* Rather than checking the actual cache line size, this code makes a
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@ -182,10 +182,27 @@ static int ath10k_htt_rx_ring_fill_n(struct ath10k_htt *htt, int num)
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static void ath10k_htt_rx_msdu_buff_replenish(struct ath10k_htt *htt)
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{
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int ret, num_to_fill;
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int ret, num_deficit, num_to_fill;
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/* Refilling the whole RX ring buffer proves to be a bad idea. The
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* reason is RX may take up significant amount of CPU cycles and starve
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* other tasks, e.g. TX on an ethernet device while acting as a bridge
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* with ath10k wlan interface. This ended up with very poor performance
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* once CPU the host system was overwhelmed with RX on ath10k.
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*
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* By limiting the number of refills the replenishing occurs
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* progressively. This in turns makes use of the fact tasklets are
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* processed in FIFO order. This means actual RX processing can starve
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* out refilling. If there's not enough buffers on RX ring FW will not
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* report RX until it is refilled with enough buffers. This
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* automatically balances load wrt to CPU power.
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*
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* This probably comes at a cost of lower maximum throughput but
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* improves the avarage and stability. */
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spin_lock_bh(&htt->rx_ring.lock);
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num_to_fill = htt->rx_ring.fill_level - htt->rx_ring.fill_cnt;
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num_deficit = htt->rx_ring.fill_level - htt->rx_ring.fill_cnt;
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num_to_fill = min(ATH10K_HTT_MAX_NUM_REFILL, num_deficit);
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num_deficit -= num_to_fill;
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ret = ath10k_htt_rx_ring_fill_n(htt, num_to_fill);
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if (ret == -ENOMEM) {
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/*
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@ -196,6 +213,8 @@ static void ath10k_htt_rx_msdu_buff_replenish(struct ath10k_htt *htt)
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*/
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mod_timer(&htt->rx_ring.refill_retry_timer, jiffies +
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msecs_to_jiffies(HTT_RX_RING_REFILL_RETRY_MS));
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} else if (num_deficit > 0) {
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tasklet_schedule(&htt->rx_replenish_task);
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}
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spin_unlock_bh(&htt->rx_ring.lock);
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}
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@ -217,6 +236,7 @@ void ath10k_htt_rx_detach(struct ath10k_htt *htt)
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int sw_rd_idx = htt->rx_ring.sw_rd_idx.msdu_payld;
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del_timer_sync(&htt->rx_ring.refill_retry_timer);
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tasklet_kill(&htt->rx_replenish_task);
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while (sw_rd_idx != __le32_to_cpu(*(htt->rx_ring.alloc_idx.vaddr))) {
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struct sk_buff *skb =
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@ -446,6 +466,12 @@ static int ath10k_htt_rx_amsdu_pop(struct ath10k_htt *htt,
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return msdu_chaining;
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}
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static void ath10k_htt_rx_replenish_task(unsigned long ptr)
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{
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struct ath10k_htt *htt = (struct ath10k_htt *)ptr;
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ath10k_htt_rx_msdu_buff_replenish(htt);
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}
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int ath10k_htt_rx_attach(struct ath10k_htt *htt)
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{
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dma_addr_t paddr;
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@ -506,6 +532,9 @@ int ath10k_htt_rx_attach(struct ath10k_htt *htt)
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if (__ath10k_htt_rx_ring_fill_n(htt, htt->rx_ring.fill_level))
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goto err_fill_ring;
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tasklet_init(&htt->rx_replenish_task, ath10k_htt_rx_replenish_task,
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(unsigned long)htt);
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ath10k_dbg(ATH10K_DBG_BOOT, "htt rx ring size %d fill_level %d\n",
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htt->rx_ring.size, htt->rx_ring.fill_level);
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return 0;
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@ -956,7 +985,7 @@ static void ath10k_htt_rx_handler(struct ath10k_htt *htt,
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}
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}
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ath10k_htt_rx_msdu_buff_replenish(htt);
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tasklet_schedule(&htt->rx_replenish_task);
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}
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static void ath10k_htt_rx_frag_handler(struct ath10k_htt *htt,
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