From: Andrew Lunn <andrew@lunn.ch>
To: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
netdev@vger.kernel.org
Subject: Re: [PATCH] net: mv643xx_eth: ensure coalesce settings survive read-modify-write
Date: Tue, 1 Nov 2016 12:10:23 +0100 [thread overview]
Message-ID: <20161101111023.GA4211@lunn.ch> (raw)
In-Reply-To: <E1c1Wdl-0000tO-Ql@rmk-PC.armlinux.org.uk>
On Tue, Nov 01, 2016 at 10:50:01AM +0000, Russell King wrote:
> The coalesce settings behave badly when changing just one value:
>
> ... # ethtool -c eth0
> rx-usecs: 249
> ... # ethtool -C eth0 tx-usecs 250
> ... # ethtool -c eth0
> rx-usecs: 248
>
> This occurs due to rounding errors when calculating the microseconds
> value - the divisons round down. This causes (eg) the rx-usecs to
> decrease by one every time the tx-usecs value is set as per the above.
>
> Fix this by making the divison round-to-nearest.
>
> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Andrew
next prev parent reply other threads:[~2016-11-01 11:10 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-01 10:50 [PATCH] net: mv643xx_eth: ensure coalesce settings survive read-modify-write Russell King
2016-11-01 11:10 ` Andrew Lunn [this message]
2016-11-01 16:18 ` David Miller
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