linux-kernel - Re: [PATCH] ath10k: increase rx buffer size to 2048

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Date:   Tue, 28 Apr 2020 05:27:25 -0700
From:   Dave Taht <dave.taht@...il.com>
To:     Kalle Valo <kvalo@...eaurora.org>
Cc:     Sven Eckelmann <sven@...fation.org>,
        ath10k <ath10k@...ts.infradead.org>,
        Linus Lüssing <linus.luessing@...3.blue>,
        Simon Wunderlich <sw@...onwunderlich.de>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        linux-wireless <linux-wireless@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ben Greear <greearb@...delatech.com>,
        "David S . Miller" <davem@...emloft.net>,
        Linus Lüssing <ll@...onwunderlich.de>,
        mail@...ianschmutzler.de
Subject: Re: [PATCH] ath10k: increase rx buffer size to 2048

On Tue, Apr 28, 2020 at 5:06 AM Kalle Valo <kvalo@...eaurora.org> wrote:
>
> Sven Eckelmann <sven@...fation.org> writes:
>
> > On Wednesday, 1 April 2020 09:00:49 CEST Sven Eckelmann wrote:
> >> On Wednesday, 5 February 2020 20:10:43 CEST Linus Lüssing wrote:
> >> > From: Linus Lüssing <ll@...onwunderlich.de>
> >> >
> >> > Before, only frames with a maximum size of 1528 bytes could be
> >> > transmitted between two 802.11s nodes.
> >> >
> >> > For batman-adv for instance, which adds its own header to each frame,
> >> > we typically need an MTU of at least 1532 bytes to be able to transmit
> >> > without fragmentation.
> >> >
> >> > This patch now increases the maxmimum frame size from 1528 to 1656
> >> > bytes.
> >> [...]
> >>
> >> @Kalle, I saw that this patch was marked as deferred [1] but I couldn't find
> >> any mail why it was done so. It seems like this currently creates real world
> >> problems - so would be nice if you could explain shortly what is currently
> >> blocking its acceptance.
> >
> > Ping?
>
> Sorry for the delay, my plan was to first write some documentation about
> different hardware families but haven't managed to do that yet.
>
> My problem with this patch is that I don't know what hardware and
> firmware versions were tested, so it needs analysis before I feel safe
> to apply it. The ath10k hardware families are very different that even
> if a patch works perfectly on one ath10k hardware it could still break
> badly on another one.
>
> What makes me faster to apply ath10k patches is to have comprehensive
> analysis in the commit log. This shows me the patch author has
> considered about all hardware families, not just the one he is testing
> on, and that I don't need to do the analysis myself.

I have been struggling to get the ath10k to sing and dance using
various variants
of the firmware, on this bug over here:

https://forum.openwrt.org/t/aql-and-the-ath10k-is-lovely/

The puzzling thing is the loss of bidirectional throughput at codel target 20,
and getting WAY more (but less than I expected) at codel target 5.

This doesn't quite have bearing the size of the rx ring, except that in my
experiments the rx ring is rather small!! and yet I get way more performance
out of it....

(still,  as you'll see from the bug, it's WAY better than it used to be)

is NAPI in this driver? I'm afraid to look.
> --
> https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches



-- 
Make Music, Not War

Dave Täht
CTO, TekLibre, LLC
http://www.teklibre.com
Tel: 1-831-435-0729