From: Andrew Lunn <andrew@lunn.ch>
To: David Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org, fugang.duan@nxp.com,
Chris.Healy@zii.aero, cphealy@gmail.com
Subject: Re: [PATCH] net: ethernet: fec: Replace interrupt driven MDIO with polled IO
Date: Wed, 15 Apr 2020 02:20:45 +0200 [thread overview]
Message-ID: <20200415002045.GF611399@lunn.ch> (raw)
In-Reply-To: <20200414.163830.2151404177947586721.davem@davemloft.net>
On Tue, Apr 14, 2020 at 04:38:30PM -0700, David Miller wrote:
> From: Andrew Lunn <andrew@lunn.ch>
> Date: Tue, 14 Apr 2020 02:45:51 +0200
>
> > Measurements of the MDIO bus have shown that driving the MDIO bus
> > using interrupts is slow. Back to back MDIO transactions take about
> > 90uS, with 25uS spent performing the transaction, and the remainder of
> > the time the bus is idle.
> >
> > Replacing the completion interrupt with polled IO results in back to
> > back transactions of 40uS. The polling loop waiting for the hardware
> > to complete the transaction takes around 27uS. Which suggests
> > interrupt handling has an overhead of 50uS, and polled IO nearly
> > halves this overhead, and doubles the MDIO performance.
> >
> > Suggested-by: Chris Heally <cphealy@gmail.com>
> > Signed-off-by: Andrew Lunn <andrew@lunn.ch>
>
> Where are we with this?
>
> Andrew, do you intend to submit a version that via iopoll.h does
> cpu relax and usleeps?
Hi David
I do want to test such a version, yes.
Andrew
next prev parent reply other threads:[~2020-04-15 0:21 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-14 0:45 [PATCH] net: ethernet: fec: Replace interrupt driven MDIO with polled IO Andrew Lunn
2020-04-14 3:07 ` [EXT] " Andy Duan
2020-04-14 3:49 ` Andrew Lunn
2020-04-14 5:12 ` Andy Duan
2020-04-14 12:55 ` Andrew Lunn
2020-04-14 23:38 ` David Miller
2020-04-15 0:20 ` Andrew Lunn [this message]
2020-04-27 15:19 ` Leonard Crestez
2020-04-27 15:29 ` Andy Duan
2020-04-27 15:37 ` Andrew Lunn
2020-04-27 16:37 ` Andrew Lunn
2020-04-27 16:48 ` Fabio Estevam
2020-04-27 16:46 ` Andrew Lunn
2020-04-27 17:48 ` [EXT] " Andy Duan
2020-04-27 20:00 ` Leonard Crestez
2020-04-27 20:13 ` Andrew Lunn
2020-04-28 7:50 ` [EXT] " Andy Duan
2020-04-28 13:34 ` Andrew Lunn
2020-04-28 13:50 ` Andy Duan
2020-04-28 14:29 ` Andrew Lunn
-- strict thread matches above, loose matches on Subject: below --
2020-10-20 2:14 Greg Ungerer
2020-10-20 2:40 ` Andrew Lunn
2020-10-21 1:51 ` Greg Ungerer
2020-10-21 13:37 ` Andrew Lunn
2020-10-22 1:14 ` Greg Ungerer
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