From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: linux-wireless@vger.kernel.org,
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>, Kan Yan <kyan@google.com>,
Rajkumar Manoharan <rmanohar@codeaurora.org>,
Kevin Hayes <kevinhayes@google.com>
Subject: Re: [PATCH v6 3/4] mac80211: Implement Airtime-based Queue Limit (AQL)
Date: Fri, 08 Nov 2019 12:10:32 +0100 [thread overview]
Message-ID: <874kzefwt3.fsf@toke.dk> (raw)
In-Reply-To: <f395a9a971ca1a0d0438fca10dfb160c421caa7a.camel@sipsolutions.net>
Johannes Berg <johannes@sipsolutions.net> writes:
> On Fri, 2019-11-08 at 11:56 +0100, Toke Høiland-Jørgensen wrote:
>> Johannes Berg <johannes@sipsolutions.net> writes:
>>
>> > On Wed, 2019-10-23 at 11:59 +0200, Toke Høiland-Jørgensen wrote:
>> > >
>> > > +void ieee80211_sta_update_pending_airtime(struct ieee80211_local *local,
>> > > + struct sta_info *sta, u8 ac,
>> > > + u16 tx_airtime, bool tx_completed)
>> > > +{
>> > > + spin_lock_bh(&local->active_txq_lock[ac]);
>> > > + if (tx_completed) {
>> > > + if (sta) {
>> > > + if (WARN_ONCE(sta->airtime[ac].aql_tx_pending < tx_airtime,
>> > > + "TXQ pending airtime underflow: %u, %u",
>> > > + sta->airtime[ac].aql_tx_pending, tx_airtime))
>> >
>> > Maybe add the STA/AC to the message?
>>
>> Can do. Any idea why we might be seeing underflows (as Kan reported)?
>
> No, I really have no idea. The shifting looked OK to me, though I didn't
> review it carefully enough to say I've really looked at all places ...
Right, bugger. I was thinking maybe there's a case where skbs can be
cloned (and retain the tx_time_est field) and then released twice? Or
maybe somewhere that steps on the skb->cb field in some other way?
Couldn't find anything obvious on a first perusal of the TX path code,
but maybe you could think of something?
Otherwise I guess we'll be forced to go and do some actual,
old-fashioned debugging ;)
-Toke
WARNING: multiple messages have this Message-ID (diff)
From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: Kan Yan <kyan@google.com>,
Rajkumar Manoharan <rmanohar@codeaurora.org>,
Kevin Hayes <kevinhayes@google.com>,
make-wifi-fast@lists.bufferbloat.net,
linux-wireless@vger.kernel.org, ath10k@lists.infradead.org,
John Crispin <john@phrozen.org>,
Lorenzo Bianconi <lorenzo@kernel.org>,
Felix Fietkau <nbd@nbd.name>
Subject: Re: [PATCH v6 3/4] mac80211: Implement Airtime-based Queue Limit (AQL)
Date: Fri, 08 Nov 2019 12:10:32 +0100 [thread overview]
Message-ID: <874kzefwt3.fsf@toke.dk> (raw)
In-Reply-To: <f395a9a971ca1a0d0438fca10dfb160c421caa7a.camel@sipsolutions.net>
Johannes Berg <johannes@sipsolutions.net> writes:
> On Fri, 2019-11-08 at 11:56 +0100, Toke Høiland-Jørgensen wrote:
>> Johannes Berg <johannes@sipsolutions.net> writes:
>>
>> > On Wed, 2019-10-23 at 11:59 +0200, Toke Høiland-Jørgensen wrote:
>> > >
>> > > +void ieee80211_sta_update_pending_airtime(struct ieee80211_local *local,
>> > > + struct sta_info *sta, u8 ac,
>> > > + u16 tx_airtime, bool tx_completed)
>> > > +{
>> > > + spin_lock_bh(&local->active_txq_lock[ac]);
>> > > + if (tx_completed) {
>> > > + if (sta) {
>> > > + if (WARN_ONCE(sta->airtime[ac].aql_tx_pending < tx_airtime,
>> > > + "TXQ pending airtime underflow: %u, %u",
>> > > + sta->airtime[ac].aql_tx_pending, tx_airtime))
>> >
>> > Maybe add the STA/AC to the message?
>>
>> Can do. Any idea why we might be seeing underflows (as Kan reported)?
>
> No, I really have no idea. The shifting looked OK to me, though I didn't
> review it carefully enough to say I've really looked at all places ...
Right, bugger. I was thinking maybe there's a case where skbs can be
cloned (and retain the tx_time_est field) and then released twice? Or
maybe somewhere that steps on the skb->cb field in some other way?
Couldn't find anything obvious on a first perusal of the TX path code,
but maybe you could think of something?
Otherwise I guess we'll be forced to go and do some actual,
old-fashioned debugging ;)
-Toke
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next prev parent reply other threads:[~2019-11-08 11:10 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-23 9:58 [PATCH v6 0/4] Add Airtime Queue Limits (AQL) to mac80211 Toke Høiland-Jørgensen
2019-10-23 9:58 ` Toke Høiland-Jørgensen
2019-10-23 9:59 ` [PATCH v6 1/4] mac80211: Shrink the size of ack_frame_id to make room for tx_time_est Toke Høiland-Jørgensen
2019-10-23 9:59 ` Toke Høiland-Jørgensen
2019-11-08 10:03 ` Johannes Berg
2019-11-08 10:03 ` Johannes Berg
2019-10-23 9:59 ` [PATCH v6 2/4] mac80211: Import airtime calculation code from mt76 Toke Høiland-Jørgensen
2019-10-23 9:59 ` Toke Høiland-Jørgensen
2019-11-08 10:07 ` Johannes Berg
2019-11-08 10:07 ` Johannes Berg
2019-11-08 10:55 ` Toke Høiland-Jørgensen
2019-11-08 10:55 ` Toke Høiland-Jørgensen
2019-11-08 10:57 ` Johannes Berg
2019-11-08 10:57 ` Johannes Berg
2019-10-23 9:59 ` [PATCH v6 3/4] mac80211: Implement Airtime-based Queue Limit (AQL) Toke Høiland-Jørgensen
2019-10-23 9:59 ` Toke Høiland-Jørgensen
2019-11-08 10:09 ` Johannes Berg
2019-11-08 10:09 ` Johannes Berg
2019-11-08 10:56 ` Toke Høiland-Jørgensen
2019-11-08 10:56 ` Toke Høiland-Jørgensen
2019-11-08 10:59 ` Johannes Berg
2019-11-08 10:59 ` Johannes Berg
2019-11-08 11:10 ` Toke Høiland-Jørgensen [this message]
2019-11-08 11:10 ` Toke Høiland-Jørgensen
2019-11-08 11:17 ` Johannes Berg
2019-11-08 11:17 ` Johannes Berg
2019-11-09 1:22 ` Kan Yan
2019-11-09 1:22 ` Kan Yan
2019-11-09 11:22 ` Toke Høiland-Jørgensen
2019-11-09 11:22 ` Toke Høiland-Jørgensen
2019-10-23 9:59 ` [PATCH v6 4/4] mac80211: Use Airtime-based Queue Limits (AQL) on packet dequeue Toke Høiland-Jørgensen
2019-10-23 9:59 ` Toke Høiland-Jørgensen
2019-11-08 10:17 ` Johannes Berg
2019-11-08 10:17 ` Johannes Berg
2019-11-08 11:01 ` Toke Høiland-Jørgensen
2019-11-08 11:01 ` Toke Høiland-Jørgensen
2019-11-08 11:05 ` Johannes Berg
2019-11-08 11:05 ` Johannes Berg
2019-11-07 6:14 ` [PATCH v6 0/4] Add Airtime Queue Limits (AQL) to mac80211 Kan Yan
2019-11-07 6:14 ` Kan Yan
2019-11-07 10:55 ` Toke Høiland-Jørgensen
2019-11-07 10:55 ` Toke Høiland-Jørgensen
2019-11-07 21:24 ` [Make-wifi-fast] " Dave Taht
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