From: Piotr Wejman <piotrwejman90@gmail.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>,
Jose Abreu <joabreu@synopsys.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>,
Maxime Coquelin <mcoquelin.stm32@gmail.com>,
netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] net: stmmac: fix rx queue priority assignment
Date: Mon, 1 Apr 2024 19:48:20 +0200 [thread overview]
Message-ID: <20240401174820.GA22684@Kalray-lp320> (raw)
In-Reply-To: <20240311134144.7b1e1a34@kernel.org>
On Mon, Mar 11, 2024 at 01:41:44PM -0700, Jakub Kicinski wrote:
> On Sun, 3 Mar 2024 20:03:38 +0100 Piotr Wejman wrote:
> > The driver should ensure that same priority is not mapped to multiple
> > rx queues. Currently rx_queue_priority() function is adding
> > priorities for a queue without clearing them from others.
>
> Do you know what user-visible mis-behavior this may result in?
When changing priority to rx queue mapping with tc qdisc taprio command (man tc-taprio),
all packets with priority assigned to multiple queues are dropped.
>
> > From DesignWare Cores Ethernet Quality-of-Service
> > Databook, section 17.1.29 MAC_RxQ_Ctrl2:
> > "[...]The software must ensure that the content of this field is
> > mutually exclusive to the PSRQ fields for other queues, that is,
> > the same priority is not mapped to multiple Rx queues[...]"
> >
> > After this patch, rx_queue_priority() function will:
> > - assign desired priorities to a queue
> > - remove those priorities from all other queues
>
> But also you seem to remove clearing all other prios from the queue:
>
> - value &= ~GMAC_RXQCTRL_PSRQX_MASK(queue);
>
> and
>
> - value &= ~XGMAC_PSRQ(queue);
>
> is that intentional? Commit message should explain why.
Yes, that keeps other priorities assigned to that queue and only clears
the same priorities from all other queues.
>
> > The write sequence of CTRL2 and CTRL3 registers is done in the way to
> > ensure this order.
>
> Ensure which order? Looks like you're actually writing in the opposite
> order than what I'd expect :S First the register you want to assign to,
> and then the register you only clear from.
>
I meant the order you wrote: first assign new priorities to a queue,
then clear them from others queues.
> When you repost please include a Fixes tag.
> --
> pw-bot: cr
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WARNING: multiple messages have this Message-ID (diff)
From: Piotr Wejman <piotrwejman90@gmail.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>,
Jose Abreu <joabreu@synopsys.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>,
Maxime Coquelin <mcoquelin.stm32@gmail.com>,
netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] net: stmmac: fix rx queue priority assignment
Date: Mon, 1 Apr 2024 19:48:20 +0200 [thread overview]
Message-ID: <20240401174820.GA22684@Kalray-lp320> (raw)
In-Reply-To: <20240311134144.7b1e1a34@kernel.org>
On Mon, Mar 11, 2024 at 01:41:44PM -0700, Jakub Kicinski wrote:
> On Sun, 3 Mar 2024 20:03:38 +0100 Piotr Wejman wrote:
> > The driver should ensure that same priority is not mapped to multiple
> > rx queues. Currently rx_queue_priority() function is adding
> > priorities for a queue without clearing them from others.
>
> Do you know what user-visible mis-behavior this may result in?
When changing priority to rx queue mapping with tc qdisc taprio command (man tc-taprio),
all packets with priority assigned to multiple queues are dropped.
>
> > From DesignWare Cores Ethernet Quality-of-Service
> > Databook, section 17.1.29 MAC_RxQ_Ctrl2:
> > "[...]The software must ensure that the content of this field is
> > mutually exclusive to the PSRQ fields for other queues, that is,
> > the same priority is not mapped to multiple Rx queues[...]"
> >
> > After this patch, rx_queue_priority() function will:
> > - assign desired priorities to a queue
> > - remove those priorities from all other queues
>
> But also you seem to remove clearing all other prios from the queue:
>
> - value &= ~GMAC_RXQCTRL_PSRQX_MASK(queue);
>
> and
>
> - value &= ~XGMAC_PSRQ(queue);
>
> is that intentional? Commit message should explain why.
Yes, that keeps other priorities assigned to that queue and only clears
the same priorities from all other queues.
>
> > The write sequence of CTRL2 and CTRL3 registers is done in the way to
> > ensure this order.
>
> Ensure which order? Looks like you're actually writing in the opposite
> order than what I'd expect :S First the register you want to assign to,
> and then the register you only clear from.
>
I meant the order you wrote: first assign new priorities to a queue,
then clear them from others queues.
> When you repost please include a Fixes tag.
> --
> pw-bot: cr
next prev parent reply other threads:[~2024-04-01 17:48 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-03 19:03 [PATCH v3] net: stmmac: fix rx queue priority assignment Piotr Wejman
2024-03-03 19:03 ` Piotr Wejman
2024-03-11 20:41 ` Jakub Kicinski
2024-03-11 20:41 ` Jakub Kicinski
2024-04-01 17:48 ` Piotr Wejman [this message]
2024-04-01 17:48 ` Piotr Wejman
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