Subject: Re: [Bugme-new] [Bug 10600] New: e1000 updates rx_bytes infrequently

From: "Michael Chan" <[email-masked]>
Date: Mon, 05 May 2008 18:55:49 -0700

On Tue, 2008-05-06 at 02:43 +0200, Krzysztof Oledzki wrote:
> Hm... strange - I tested it on 2.6.23.17 with:
> 03:00.0 Ethernet controller: Broadcom Corporation NetXtreme II BCM5708
> Gigabit Ethernet (rev 12)
> 
> Setting both:
>   # ethtool -C eth0 stats-block-usecs 50
> and:
>   # ethtool -C eth0 stats-block-usecs 5000000
> gives exactly the same situation - statistics update frequency is
> still ~1s.
> 
> # ethtool -c eth1 |grep stats-block-usecs
> stats-block-usecs: 999936

Unfortunately, 5708 has a bug in the statistics DMA engine that was
reported here on netdev about 1 year ago.  To work around it, we have to
disable the statistics block DMA and rely on the driver's timer function
which runs at a fixed 1 second interval.  So only 0 and 999936 are
allowed values on the 5708.  Newer chips or the older 5706 do not have
this problem.