On 10/17/2013 05:04 AM, Stanislaw Gruszka wrote:
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@xxxxxxxxxxxxxxx Signed-off-by: Stanislaw Gruszka <sgruszka@xxxxxxxxxx> --- drivers/net/wireless/rt2x00/rt2800usb.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/net/wireless/rt2x00/rt2800usb.c b/drivers/net/wireless/rt2x00/rt2800usb.c index 96677ce5..e095e61 100644 --- a/drivers/net/wireless/rt2x00/rt2800usb.c +++ b/drivers/net/wireless/rt2x00/rt2800usb.c @@ -176,8 +176,8 @@ 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, 1000000), HRTIMER_MODE_REL); return false; } @@ -202,8 +202,8 @@ 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, 2000000), HRTIMER_MODE_REL); }
I suggest getting rid of the magic numbers as long as you are making this change. A single define could handle the delay time for the two cases.
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