From: Ben Greear <greearb@candelatech.com>
To: Michal Kazior <michal.kazior@tieto.com>
Cc: make-wifi-fast@lists.bufferbloat.net,
"codel@lists.bufferbloat.net" <codel@lists.bufferbloat.net>,
linux-wireless <linux-wireless@vger.kernel.org>,
Dave Taht <dave.taht@gmail.com>,
"ath10k@lists.infradead.org" <ath10k@lists.infradead.org>
Subject: Re: [RFC] ath10k: implement dql for htt tx
Date: Wed, 30 Mar 2016 08:28:36 -0700 [thread overview]
Message-ID: <56FBF0A4.5090508@candelatech.com> (raw)
In-Reply-To: <CA+BoTQnBadqR4F2OSwLhiqXebzRRdLOWabHmeVQVGnSSm9vVfQ@mail.gmail.com>
On 03/30/2016 02:22 AM, Michal Kazior wrote:
> On 29 March 2016 at 17:54, Ben Greear <greearb@candelatech.com> wrote:
>> On 03/29/2016 12:49 AM, Michal Kazior wrote:
>>
>>>> if you are getting a pure codel result of 160ms, that means the
>>>> implementation is broken. But I think (after having read your
>>>> description twice), the baseline result today of 160ms of queuing was
>>>> with a fq_codel *qdisc* doing the work on top of huge buffers,
>>>
>>>
>>> Yes. The 160ms is with fq_codel qdisc with ath10k doing DQL at 6mbps.
>>> Without DQL ath10k would clog up all tx slots (1424 of them) with
>>> frames. At 6mbps you typically want/need a handful (5-10) of frames to
>>> be queued.
>>
>>
>> Have you actually verified you can use all tx slots?
>
> It works in most cases. I guess you're suspecting some of your
> tx(flushing?) problems might be induced by overcommiting?
>
>> The way the
>> firmware uses it's tx buffers I think you may not be able to actually
>> do that...and in practice, you will get a lot fewer usable tx-buffers
>> than configured....
>
> Could be, e.g. I'm aware management frames are kind of a special case
> in recent firmware revisions.
>
> What would/do you expect firmware would/will do when we overcommit?
> The driver does advertise number of HTT tx slots so I would expect it
> to work fine if it didn't crash during boot.
The firmware will return something like tx-dropped immediately. The reason
is that the firmware keeps more than one internal priority queue, and in general, reserves
some of the tx-descriptors for high priority.
So, you never see tx-queues completely full in the driver, so tx queues are
not stopped farther up the stack.
Possibly I am confused about some of this, so I'm quite curious if you ever see
tx-queues determined to be full in the ath10k driver.
Thanks,
Ben
--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc http://www.candelatech.com
_______________________________________________
ath10k mailing list
ath10k@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/ath10k
WARNING: multiple messages have this Message-ID (diff)
From: Ben Greear <greearb@candelatech.com>
To: Michal Kazior <michal.kazior@tieto.com>
Cc: Dave Taht <dave.taht@gmail.com>,
"ath10k@lists.infradead.org" <ath10k@lists.infradead.org>,
linux-wireless <linux-wireless@vger.kernel.org>,
make-wifi-fast@lists.bufferbloat.net,
"codel@lists.bufferbloat.net" <codel@lists.bufferbloat.net>
Subject: Re: [RFC] ath10k: implement dql for htt tx
Date: Wed, 30 Mar 2016 08:28:36 -0700 [thread overview]
Message-ID: <56FBF0A4.5090508@candelatech.com> (raw)
In-Reply-To: <CA+BoTQnBadqR4F2OSwLhiqXebzRRdLOWabHmeVQVGnSSm9vVfQ@mail.gmail.com>
On 03/30/2016 02:22 AM, Michal Kazior wrote:
> On 29 March 2016 at 17:54, Ben Greear <greearb@candelatech.com> wrote:
>> On 03/29/2016 12:49 AM, Michal Kazior wrote:
>>
>>>> if you are getting a pure codel result of 160ms, that means the
>>>> implementation is broken. But I think (after having read your
>>>> description twice), the baseline result today of 160ms of queuing was
>>>> with a fq_codel *qdisc* doing the work on top of huge buffers,
>>>
>>>
>>> Yes. The 160ms is with fq_codel qdisc with ath10k doing DQL at 6mbps.
>>> Without DQL ath10k would clog up all tx slots (1424 of them) with
>>> frames. At 6mbps you typically want/need a handful (5-10) of frames to
>>> be queued.
>>
>>
>> Have you actually verified you can use all tx slots?
>
> It works in most cases. I guess you're suspecting some of your
> tx(flushing?) problems might be induced by overcommiting?
>
>> The way the
>> firmware uses it's tx buffers I think you may not be able to actually
>> do that...and in practice, you will get a lot fewer usable tx-buffers
>> than configured....
>
> Could be, e.g. I'm aware management frames are kind of a special case
> in recent firmware revisions.
>
> What would/do you expect firmware would/will do when we overcommit?
> The driver does advertise number of HTT tx slots so I would expect it
> to work fine if it didn't crash during boot.
The firmware will return something like tx-dropped immediately. The reason
is that the firmware keeps more than one internal priority queue, and in general, reserves
some of the tx-descriptors for high priority.
So, you never see tx-queues completely full in the driver, so tx queues are
not stopped farther up the stack.
Possibly I am confused about some of this, so I'm quite curious if you ever see
tx-queues determined to be full in the ath10k driver.
Thanks,
Ben
--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc http://www.candelatech.com
next prev parent reply other threads:[~2016-03-30 15:29 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-25 9:39 [RFC] ath10k: implement dql for htt tx Michal Kazior
2016-03-25 9:39 ` Michal Kazior
[not found] ` <CA+BoTQk7q7VerNC1KZK49REHn9rfo6sG5zW54P=-K3XkOL77pQ@mail.gmail.com>
2016-03-26 16:44 ` Dave Taht
2016-03-26 16:44 ` Dave Taht
2016-03-29 7:49 ` Michal Kazior
2016-03-29 7:49 ` Michal Kazior
2016-03-29 15:54 ` Ben Greear
2016-03-29 15:54 ` Ben Greear
2016-03-30 9:22 ` Michal Kazior
2016-03-30 9:22 ` Michal Kazior
2016-03-30 15:28 ` Ben Greear [this message]
2016-03-30 15:28 ` Ben Greear
2016-03-31 6:39 ` Michal Kazior
2016-03-31 6:39 ` Michal Kazior
2016-03-30 0:57 ` Dave Taht
2016-03-30 0:57 ` Dave Taht
2016-03-30 10:04 ` Michal Kazior
2016-03-30 10:04 ` Michal Kazior
2016-04-01 8:01 ` Michal Kazior
2016-04-01 8:01 ` Michal Kazior
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