Re: [PATCH] ath9k: Print has_queued in debugfs.

["Toke Høiland-Jørgensen" <toke@toke.dk>]

Ben Greear <greearb@candelatech.com> writes:

> On 01/27/2018 05:29 AM, Toke H=C3=B8iland-J=C3=B8rgensen wrote:
>> greearb@candelatech.com writes:
>>
>>> From: Ben Greear <greearb@candelatech.com>
>>>
>>> The PAUSED field was never printed per tid.  Replace that
>>> with has_queued, which might help someone track down strange
>>> bugs related to aqm.
>>>
>>> And, make tx-queue debug info show peer BSSID as well as vdev
>>> MAC to aid debugging with multiple stations connected to the
>>> same peer.
>>>
>>> Signed-off-by: Ben Greear <greearb@candelatech.com>
>>> ---
>>>  drivers/net/wireless/ath/ath9k/debug_sta.c | 10 ++++++----
>>>  drivers/net/wireless/ath/ath9k/xmit.c      |  5 +++--
>>>  2 files changed, 9 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/drivers/net/wireless/ath/ath9k/debug_sta.c b/drivers/net/w=
ireless/ath/ath9k/debug_sta.c
>>> index efc692e..a45f1f5 100644
>>> --- a/drivers/net/wireless/ath/ath9k/debug_sta.c
>>> +++ b/drivers/net/wireless/ath/ath9k/debug_sta.c
>>> @@ -48,9 +48,10 @@ static ssize_t read_file_node_aggr(struct file *file=
, char __user *user_buf,
>>>  			 an->mpdudensity);
>>>
>>>  	len +=3D scnprintf(buf + len, size - len,
>>> -			 "\n%3s%11s%10s%10s%10s%10s%9s%6s%8s\n",
>>> +			 "\n%3s%11s%10s%10s%10s%10s%9s%6s%9s\n",
>>>  			 "TID", "SEQ_START", "SEQ_NEXT", "BAW_SIZE",
>>> -			 "BAW_HEAD", "BAW_TAIL", "BAR_IDX", "SCHED", "PAUSED");
>>> +			 "BAW_HEAD", "BAW_TAIL", "BAR_IDX", "SCHED",
>>> +			 "HAS-QUED");
>>>
>>>  	for (tidno =3D 0; tidno < IEEE80211_NUM_TIDS; tidno++) {
>>>  		tid =3D ath_node_to_tid(an, tidno);
>>> @@ -58,7 +59,7 @@ static ssize_t read_file_node_aggr(struct file *file,=
 char __user *user_buf,
>>>  		ath_txq_lock(sc, txq);
>>>  		if (tid->active) {
>>>  			len +=3D scnprintf(buf + len, size - len,
>>> -					 "%3d%11d%10d%10d%10d%10d%9d%6d\n",
>>> +					 "%3d%11d%10d%10d%10d%10d%9d%6d%9d\n",
>>>  					 tid->tidno,
>>>  					 tid->seq_start,
>>>  					 tid->seq_next,
>>> @@ -66,7 +67,8 @@ static ssize_t read_file_node_aggr(struct file *file,=
 char __user *user_buf,
>>>  					 tid->baw_head,
>>>  					 tid->baw_tail,
>>>  					 tid->bar_index,
>>> -					 !list_empty(&tid->list));
>>> +					 !list_empty(&tid->list),
>>> +					 tid->has_queued);
>>
>> Would it perhaps be useful to print the length of tid->retry_q instead
>> of / in addition to has_queued? Planning to get rid of the has_queued
>> variable entirely...
>
> I'm just getting started looking at this. 4.9 kernel works fine, so it
> seems to be a regression in the aqm stuff since that is the big change
> between 4.9 and 4.13.
>
> From a brief look yesterday, it seems that has_queued is not
> adequately protected by locks, but also, it was '1', which indicates
> it wants to send pkts (?), so I guess it was not hitting a locking
> race.

It's only ever accessed under ath_txq_lock(), so I don't think it's a
locking issue.

> Can you point me at the scheduler code (method name?). I'll be looking
> at that as soon as I get time.

ath_txq_schedule() is the main scheduler (in xmit.c). As I said it may
be the airtime fairness scheduler that's throttling stations; did you
look at the airtime debugfs file?

-Toke