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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>
This commit is contained in:
Michal Kazior 2013-09-24 10:18:36 +02:00 committed by Kalle Valo
parent 4d316c79a5
commit 6e712d427c
2 changed files with 38 additions and 3 deletions
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6
drivers/net/wireless/ath/ath10k/htt.h
View File

@ -19,6 +19,7 @@
#define _HTT_H_
#include <linux/bug.h>
#include <linux/interrupt.h>
#include "htc.h"
#include "rx_desc.h"
@ -1268,6 +1269,7 @@ struct ath10k_htt {
/* set if host-fw communication goes haywire
* used to avoid further failures */
bool rx_confused;
struct tasklet_struct rx_replenish_task;
};
#define RX_HTT_HDR_STATUS_LEN 64
@ -1308,6 +1310,10 @@ struct htt_rx_desc {
#define HTT_RX_BUF_SIZE 1920
#define HTT_RX_MSDU_SIZE (HTT_RX_BUF_SIZE - (int)sizeof(struct htt_rx_desc))
/* Refill a bunch of RX buffers for each refill round so that FW/HW can handle
* aggregated traffic more nicely. */
#define ATH10K_HTT_MAX_NUM_REFILL 16
/*
* DMA_MAP expects the buffer to be an integral number of cache lines.
* Rather than checking the actual cache line size, this code makes a

35
drivers/net/wireless/ath/ath10k/htt_rx.c
View File

@ -182,10 +182,27 @@ static int ath10k_htt_rx_ring_fill_n(struct ath10k_htt *htt, int num)
static void ath10k_htt_rx_msdu_buff_replenish(struct ath10k_htt *htt)
{
int ret, num_to_fill;
int ret, num_deficit, num_to_fill;
/* Refilling the whole RX ring buffer proves to be a bad idea. The
* reason is RX may take up significant amount of CPU cycles and starve
* other tasks, e.g. TX on an ethernet device while acting as a bridge
* with ath10k wlan interface. This ended up with very poor performance
* once CPU the host system was overwhelmed with RX on ath10k.
*
* By limiting the number of refills the replenishing occurs
* progressively. This in turns makes use of the fact tasklets are
* processed in FIFO order. This means actual RX processing can starve
* out refilling. If there's not enough buffers on RX ring FW will not
* report RX until it is refilled with enough buffers. This
* automatically balances load wrt to CPU power.
*
* This probably comes at a cost of lower maximum throughput but
* improves the avarage and stability. */
spin_lock_bh(&htt->rx_ring.lock);
num_to_fill = htt->rx_ring.fill_level - htt->rx_ring.fill_cnt;
num_deficit = htt->rx_ring.fill_level - htt->rx_ring.fill_cnt;
num_to_fill = min(ATH10K_HTT_MAX_NUM_REFILL, num_deficit);
num_deficit -= num_to_fill;
ret = ath10k_htt_rx_ring_fill_n(htt, num_to_fill);
if (ret == -ENOMEM) {
/*
@ -196,6 +213,8 @@ static void ath10k_htt_rx_msdu_buff_replenish(struct ath10k_htt *htt)
*/
mod_timer(&htt->rx_ring.refill_retry_timer, jiffies +
msecs_to_jiffies(HTT_RX_RING_REFILL_RETRY_MS));
} else if (num_deficit > 0) {
tasklet_schedule(&htt->rx_replenish_task);
}
spin_unlock_bh(&htt->rx_ring.lock);
}
@ -217,6 +236,7 @@ void ath10k_htt_rx_detach(struct ath10k_htt *htt)
int sw_rd_idx = htt->rx_ring.sw_rd_idx.msdu_payld;
del_timer_sync(&htt->rx_ring.refill_retry_timer);
tasklet_kill(&htt->rx_replenish_task);
while (sw_rd_idx != __le32_to_cpu(*(htt->rx_ring.alloc_idx.vaddr))) {
struct sk_buff *skb =
@ -446,6 +466,12 @@ static int ath10k_htt_rx_amsdu_pop(struct ath10k_htt *htt,
return msdu_chaining;
}
static void ath10k_htt_rx_replenish_task(unsigned long ptr)
{
struct ath10k_htt *htt = (struct ath10k_htt *)ptr;
ath10k_htt_rx_msdu_buff_replenish(htt);
}
int ath10k_htt_rx_attach(struct ath10k_htt *htt)
{
dma_addr_t paddr;
@ -506,6 +532,9 @@ int ath10k_htt_rx_attach(struct ath10k_htt *htt)
if (__ath10k_htt_rx_ring_fill_n(htt, htt->rx_ring.fill_level))
goto err_fill_ring;
tasklet_init(&htt->rx_replenish_task, ath10k_htt_rx_replenish_task,
(unsigned long)htt);
ath10k_dbg(ATH10K_DBG_BOOT, "htt rx ring size %d fill_level %d\n",
htt->rx_ring.size, htt->rx_ring.fill_level);
return 0;
@ -956,7 +985,7 @@ static void ath10k_htt_rx_handler(struct ath10k_htt *htt,
}
}
ath10k_htt_rx_msdu_buff_replenish(htt);
tasklet_schedule(&htt->rx_replenish_task);
}
static void ath10k_htt_rx_frag_handler(struct ath10k_htt *htt,