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Message-Id: <20190307.093210.37594449620142618.davem@davemloft.net>
Date: Thu, 07 Mar 2019 09:32:10 -0800 (PST)
From: David Miller <davem@...emloft.net>
To: horms+renesas@...ge.net.au
Cc: sergei.shtylyov@...entembedded.com, magnus.damm@...il.com,
netdev@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
wsa+renesas@...g-engineering.com
Subject: Re: [PATCH net] ravb: Decrease TxFIFO depth of Q3 and Q2 to one
From: Simon Horman <horms+renesas@...ge.net.au>
Date: Thu, 7 Mar 2019 11:24:47 +0100
> From: Masaru Nagai <masaru.nagai.vx@...esas.com>
>
> Hardware has the CBS (Credit Based Shaper) which affects only Q3
> and Q2. When updating the CBS settings, even if the driver does so
> after waiting for Tx DMA finished, there is a possibility that frame
> data still remains in TxFIFO.
>
> To avoid this, decrease TxFIFO depth of Q3 and Q2 to one.
>
> This patch has been exercised this using netperf TCP_MAERTS, TCP_STREAM
> and UDP_STREAM tests run on an Ebisu board. No performance change was
> detected, outside of noise in the tests, both in terms of throughput and
> CPU utilisation.
>
> Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
> Signed-off-by: Masaru Nagai <masaru.nagai.vx@...esas.com>
> Signed-off-by: Kazuya Mizuguchi <kazuya.mizuguchi.ks@...esas.com>
> [simon: updated changelog]
> Signed-off-by: Simon Horman <horms+renesas@...ge.net.au>
Applied and queued up for -stable, thanks.
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