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From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Kan Yan <kyan@google.com>
Cc: Johannes Berg <johannes@sipsolutions.net>,
	linux-wireless@vger.kernel.org,
	Make-Wifi-fast <make-wifi-fast@lists.bufferbloat.net>,
	ath10k@lists.infradead.org, John Crispin <john@phrozen.org>,
	Lorenzo Bianconi <lorenzo@kernel.org>,
	Felix Fietkau <nbd@nbd.name>,
	Rajkumar Manoharan <rmanohar@codeaurora.org>,
	Kevin Hayes <kevinhayes@google.com>
Subject: Re: [PATCH v4 4/4] mac80211: Use Airtime-based Queue Limits (AQL) on packet dequeue
Date: Wed, 23 Oct 2019 11:52:02 +0200	[thread overview]
Message-ID: <87lftbn60t.fsf@toke.dk> (raw)
In-Reply-To: <87tv7znact.fsf@toke.dk>

Toke Høiland-Jørgensen <toke@redhat.com> writes:

> Kan Yan <kyan@google.com> writes:
>
>>> >> +               if (ieee80211_is_data_qos(hdr->frame_control)) {
>>> >> +                       qc = ieee80211_get_qos_ctl(hdr);
>>> >> +                       tid = qc[0] & 0xf;
>>> >> +                       ac = ieee80211_ac_from_tid(tid);
>>> >> +               } else {
>>> >> +                       ac = IEEE80211_AC_BE;
>>> >> +               }
>>> >
>>> > The tid/ac is incorrect either here or in __ieee80211_tx_status() when
>>> > tested with ath10k. The ac is set to AC_BE with test done using BK
>>> > class traffic, hence the pending airtime get updated for the wrong
>>> > txq.
>>>
>>> Huh, well that won't do, obviously :)
>>>
>>> Any idea why it might be wrong?
>>
>> somehow  ieee80211_is_data_qos() returns false. Besides,  qos_control
>> field doesn't seems to be set in ieee80211_build_hdr().
>>
>>> Hmm, I guess we could just get the ac using skb_get_queue_mapping().
>>> I'll send an update with this fixed for you to try :)
>> Thanks for the quick update. It is getting much better, but
>> unfortunately the pending airtime accounting sometimes is still not
>> correct and cause txq stuck occasionally.
>
> OK, so that has to mean that there are packets getting dropped somewhere
> without going through ieee80211_report_used_skb(). Assuming you're not
> hitting the underflow warnings, just seeing the counter not get back
> down to zero?
>
> Could you see if you can find out if ath10k does that anywhere? I'll go
> hunting in mac80211.
>
> Looking for calls to kfree_skb() or kfree_skb_list() should hopefully
> turn up something...

Aha! Turns out I was doing the sta lookup completely wrong in
ieee80211_report_used_skb(); so anything frames that were dropped and
went through there would not get its airtime subtracted correctly. Will
send a v6 with a fix :)

-Toke


WARNING: multiple messages have this Message-ID
From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Kan Yan <kyan@google.com>
Cc: Rajkumar Manoharan <rmanohar@codeaurora.org>,
	Kevin Hayes <kevinhayes@google.com>,
	Make-Wifi-fast <make-wifi-fast@lists.bufferbloat.net>,
	linux-wireless@vger.kernel.org, ath10k@lists.infradead.org,
	John Crispin <john@phrozen.org>,
	Johannes Berg <johannes@sipsolutions.net>,
	Lorenzo Bianconi <lorenzo@kernel.org>,
	Felix Fietkau <nbd@nbd.name>
Subject: Re: [PATCH v4 4/4] mac80211: Use Airtime-based Queue Limits (AQL) on packet dequeue
Date: Wed, 23 Oct 2019 11:52:02 +0200	[thread overview]
Message-ID: <87lftbn60t.fsf@toke.dk> (raw)
In-Reply-To: <87tv7znact.fsf@toke.dk>

Toke Høiland-Jørgensen <toke@redhat.com> writes:

> Kan Yan <kyan@google.com> writes:
>
>>> >> +               if (ieee80211_is_data_qos(hdr->frame_control)) {
>>> >> +                       qc = ieee80211_get_qos_ctl(hdr);
>>> >> +                       tid = qc[0] & 0xf;
>>> >> +                       ac = ieee80211_ac_from_tid(tid);
>>> >> +               } else {
>>> >> +                       ac = IEEE80211_AC_BE;
>>> >> +               }
>>> >
>>> > The tid/ac is incorrect either here or in __ieee80211_tx_status() when
>>> > tested with ath10k. The ac is set to AC_BE with test done using BK
>>> > class traffic, hence the pending airtime get updated for the wrong
>>> > txq.
>>>
>>> Huh, well that won't do, obviously :)
>>>
>>> Any idea why it might be wrong?
>>
>> somehow  ieee80211_is_data_qos() returns false. Besides,  qos_control
>> field doesn't seems to be set in ieee80211_build_hdr().
>>
>>> Hmm, I guess we could just get the ac using skb_get_queue_mapping().
>>> I'll send an update with this fixed for you to try :)
>> Thanks for the quick update. It is getting much better, but
>> unfortunately the pending airtime accounting sometimes is still not
>> correct and cause txq stuck occasionally.
>
> OK, so that has to mean that there are packets getting dropped somewhere
> without going through ieee80211_report_used_skb(). Assuming you're not
> hitting the underflow warnings, just seeing the counter not get back
> down to zero?
>
> Could you see if you can find out if ath10k does that anywhere? I'll go
> hunting in mac80211.
>
> Looking for calls to kfree_skb() or kfree_skb_list() should hopefully
> turn up something...

Aha! Turns out I was doing the sta lookup completely wrong in
ieee80211_report_used_skb(); so anything frames that were dropped and
went through there would not get its airtime subtracted correctly. Will
send a v6 with a fix :)

-Toke


_______________________________________________
ath10k mailing list
ath10k@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/ath10k

  reply	other threads:[~2019-10-23  9:52 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-19 11:37 [PATCH v4 0/4] Add Airtime Queue Limits (AQL) to mac80211 Toke Høiland-Jørgensen
2019-10-19 11:37 ` Toke Høiland-Jørgensen
2019-10-19 11:37 ` [PATCH v4 1/4] mac80211: Shrink the size of ack_frame_id to make room for tx_time_est Toke Høiland-Jørgensen
2019-10-19 11:37   ` Toke Høiland-Jørgensen
2019-10-19 11:37 ` [PATCH v4 2/4] mac80211: Import airtime calculation code from mt76 Toke Høiland-Jørgensen
2019-10-19 11:37   ` Toke Høiland-Jørgensen
2019-10-21 22:14   ` kbuild test robot
2019-10-21 22:14     ` kbuild test robot
2019-10-21 22:14   ` [RFC PATCH] mac80211: ieee80211_calc_rx_airtime() can be static kbuild test robot
2019-10-21 22:14     ` kbuild test robot
2019-10-19 11:37 ` [PATCH v4 3/4] mac80211: Implement Airtime-based Queue Limit (AQL) Toke Høiland-Jørgensen
2019-10-19 11:37   ` Toke Høiland-Jørgensen
2019-10-19 11:37 ` [PATCH v4 4/4] mac80211: Use Airtime-based Queue Limits (AQL) on packet dequeue Toke Høiland-Jørgensen
2019-10-19 11:37   ` Toke Høiland-Jørgensen
2019-10-22  6:20   ` Kan Yan
2019-10-22  6:20     ` Kan Yan
2019-10-22  7:14     ` Toke Høiland-Jørgensen
2019-10-22  7:14       ` Toke Høiland-Jørgensen
2019-10-22 11:35     ` Toke Høiland-Jørgensen
2019-10-22 11:35       ` Toke Høiland-Jørgensen
2019-10-23  6:41       ` Kan Yan
2019-10-23  6:41         ` Kan Yan
2019-10-23  8:18         ` Toke Høiland-Jørgensen
2019-10-23  8:18           ` Toke Høiland-Jørgensen
2019-10-23  9:52           ` Toke Høiland-Jørgensen [this message]
2019-10-23  9:52             ` Toke Høiland-Jørgensen
2019-10-23 15:43             ` Kan Yan
2019-10-23 15:43               ` Kan Yan
     [not found]             ` <CA+iem5vU-K-+sSSeNugy5ZZF_nH5vuaXW3J_WC=1WWhdkHOgjw@mail.gmail.com>
2019-10-23 21:09               ` Toke Høiland-Jørgensen
2019-10-23 21:09                 ` Toke Høiland-Jørgensen

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