Re: [PATCH] s2io: read rx_packets count from the hardware stats

[David Miller <davem@davemloft.net>]

From: Michal Schmidt <mschmidt@redhat.com>
Date: Fri, 25 Jun 2010 01:32:32 +0200

> Most of the statistics the s2io driver provides in /proc/net/dev
> it reads directly from the hardware counters. For some reason it does
> not do that for rx_packets. It counts rx_packets purely in software.
> 
> A customer reported a bug where in /proc/net/dev the 'multicast' counter
> was increasing faster than 'packets' ( = rx_packets in the source code).
> This confuses userspace, especially snmpd.
> 
> The hardware provides a counter for the total number of received
> frames (RMAC_VLD_FRMS) which the driver can use for the rx_packets
> statistic. By reading both statistics from the hardware it makes sure
> that all multicast frames are included in the total.
> 
> The customer tested a patch like this (only modified for RHEL5) with
> S2io Inc. Xframe II 10Gbps Ethernet (rev 02)
> and it fixed the problem.
> 
> Signed-off-by: Michal Schmidt <mschmidt@redhat.com>

Please also use the rmac_data_octets HW statistic for rx_bytes
otherwise rx_bytes will be out of sync with the other stats too.