linux-kernel - Re: [PATCH net-next 3/3] net: stmmac: Introducing support for Page Pool

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Date:   Fri, 26 Jul 2019 15:11:00 +0100
From:   Jon Hunter <jonathanh@...dia.com>
To:     Jose Abreu <Jose.Abreu@...opsys.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
CC:     Joao Pinto <Joao.Pinto@...opsys.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        linux-tegra <linux-tegra@...r.kernel.org>,
        Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Robin Murphy <robin.murphy@....com>,
        "David S . Miller" <davem@...emloft.net>
Subject: Re: [PATCH net-next 3/3] net: stmmac: Introducing support for Page
 Pool


On 25/07/2019 16:12, Jose Abreu wrote:
> From: Jon Hunter <jonathanh@...dia.com>
> Date: Jul/25/2019, 15:25:59 (UTC+00:00)
> 
>>
>> On 25/07/2019 14:26, Jose Abreu wrote:
>>
>> ...
>>
>>> Well, I wasn't expecting that :/
>>>
>>> Per documentation of barriers I think we should set descriptor fields 
>>> and then barrier and finally ownership to HW so that remaining fields 
>>> are coherent before owner is set.
>>>
>>> Anyway, can you also add a dma_rmb() after the call to 
>>> stmmac_rx_status() ?
>>
>> Yes. I removed the debug print added the barrier, but that did not help.
> 
> So, I was finally able to setup NFS using your replicated setup and I 
> can't see the issue :(
> 
> The only difference I have from yours is that I'm using TCP in NFS 
> whilst you (I believe from the logs), use UDP.

So I tried TCP by setting the kernel boot params to 'nfsvers=3' and
'proto=tcp' and this does appear to be more stable, but not 100% stable.
It still appears to fail in the same place about 50% of the time.

> You do have flow control active right ? And your HW FIFO size is >= 4k ?

How can I verify if flow control is active?

The documentation for this device indicates a max transfer size of 16kB
for TX and RX.

Cheers
Jon

-- 
nvpublic