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SubjectRe: [PATCH v2] net: mvneta: Fix Serdes configuration for 2.5Gbps modes
On Fri, Jun 12, 2020 at 01:52:50PM +0200, Sascha Hauer wrote:
> On Fri, Jun 12, 2020 at 12:30:31PM +0100, Russell King - ARM Linux admin wrote:
> > On Fri, Jun 12, 2020 at 12:22:13PM +0100, Russell King - ARM Linux admin wrote:
> > > On Fri, Jun 12, 2020 at 11:42:08AM +0100, Russell King - ARM Linux admin wrote:
> > > > With the obvious mistakes fixed (extraneous 'i' and lack of default
> > > > case), it seems to still work on Armada 388 Clearfog Pro with 2.5G
> > > > modules.
> > >
> > > ... and the other bug fixed - mvneta_comphy_init() needs to be passed
> > > the interface mode.
> >
> > Unrelated to the patch, has anyone noticed that mvneta's performance
> > seems to have reduced? I've only just noticed it (which makes 2.5Gbps
> > rather pointless). This is iperf between two clearfogs with a 2.5G
> > fibre link:
> >
> > root@clearfog21:~# iperf -V -c fe80::250:43ff:fe02:303%eno2
> > ------------------------------------------------------------
> > Client connecting to fe80::250:43ff:fe02:303%eno2, TCP port 5001
> > TCP window size: 43.8 KByte (default)
> > ------------------------------------------------------------
> > [ 3] local fe80::250:43ff:fe21:203 port 48928 connected with fe80::250:43ff:fe02:303 port 5001
> > [ ID] Interval Transfer Bandwidth
> > [ 3] 0.0-10.0 sec 553 MBytes 464 Mbits/sec
> >
> > I checked with Jon Nettleton, and he confirms my recollection that
> > mvneta on Armada 388 used to be able to fill a 2.5Gbps link.
> >
> > If Armada 388 can't manage, then I suspect Armada XP will have worse
> > performance being an earlier revision SoC.
>
> I only have one board with a Armada XP here which has a loopback cable
> between two ports. It gives me:
>
> [ 3] local 172.16.1.4 port 47002 connected with 172.16.1.0 port 5001
> [ ID] Interval Transfer Bandwidth
> [ 3] 0.0-10.0 sec 1.27 GBytes 1.09 Gbits/sec
>
> Still not 2.5Gbps, but at least twice the data rate you get, plus my
> board has to handle both ends of the link.

It turns out I still had various locking debugs and DMA API debug
enabled:

[ 3] local fe80::250:43ff:fe21:203 port 39326 connected with fe80::250:43ff:fe02:303 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 2.70 GBytes 2.32 Gbits/sec

... which is more like it for this platform!

--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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