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rt2800usb: slow down TX status polling 

Polling TX statuses too frequently has two negative effects. First is
randomly peek CPU usage, causing overall system functioning delays.
Second bad effect is that device is not able to fill TX statuses in
H/W register on some workloads and we get lot of timeouts like below:

ieee80211 phy4: rt2800usb_entry_txstatus_timeout: Warning - TX status timeout for entry 7 in queue 2
ieee80211 phy4: rt2800usb_entry_txstatus_timeout: Warning - TX status timeout for entry 7 in queue 2
ieee80211 phy4: rt2800usb_txdone: Warning - Got TX status for an empty queue 2, dropping

This not only cause flood of messages in dmesg, but also bad throughput,
since rate scaling algorithm can not work optimally.

In the future, we should probably make polling interval be adjusted
automatically, but for now just increase values, this make mentioned
problems gone.

Resolve:
https://bugzilla.kernel.org/show_bug.cgi?id=62781

Cc: stable@vger.kernel.org
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Stanislaw Gruszka 2013-10-18 11:36:54 +02:00 committed by John W. Linville
parent 5671ab05cf
commit 36165fd5b0
1 changed files with 8 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
drivers/net/wireless/rt2x00/rt2800usb.c
View File

@ -148,6 +148,8 @@ static bool rt2800usb_txstatus_timeout(struct rt2x00_dev *rt2x00dev)
return false;
}
#define TXSTATUS_READ_INTERVAL 1000000
static bool rt2800usb_tx_sta_fifo_read_completed(struct rt2x00_dev *rt2x00dev,
int urb_status, u32 tx_status)
{
@ -176,8 +178,9 @@ static bool rt2800usb_tx_sta_fifo_read_completed(struct rt2x00_dev *rt2x00dev,
queue_work(rt2x00dev->workqueue, &rt2x00dev->txdone_work);
if (rt2800usb_txstatus_pending(rt2x00dev)) {
/* Read register after 250 us */
hrtimer_start(&rt2x00dev->txstatus_timer, ktime_set(0, 250000),
/* Read register after 1 ms */
hrtimer_start(&rt2x00dev->txstatus_timer,
ktime_set(0, TXSTATUS_READ_INTERVAL),
HRTIMER_MODE_REL);
return false;
}
@ -202,8 +205,9 @@ static void rt2800usb_async_read_tx_status(struct rt2x00_dev *rt2x00dev)
if (test_and_set_bit(TX_STATUS_READING, &rt2x00dev->flags))
return;
/* Read TX_STA_FIFO register after 500 us */
hrtimer_start(&rt2x00dev->txstatus_timer, ktime_set(0, 500000),
/* Read TX_STA_FIFO register after 2 ms */
hrtimer_start(&rt2x00dev->txstatus_timer,
ktime_set(0, 2*TXSTATUS_READ_INTERVAL),
HRTIMER_MODE_REL);
}