netdev - [PATCH] ixgbevf - Prevent RX/TX statistics getting reset to zero

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Message-ID: <E31FB011129F30488D5861F38390491520D00B9F01@BLRX7MCDC201.AMER.DELL.COM>
Date:	Thu, 12 Jul 2012 06:55:21 -0700
From:	<Narendra_K@...l.com>
To:	<netdev@...r.kernel.org>
Subject: [PATCH] ixgbevf - Prevent RX/TX statistics getting reset to zero

Hello,

[Apologies if you are receiving this message twice. I am resending the message, as I got message delivery failure note].

While exploring SR-IOV on Intel 82599EB 10-Gigabit SFP+ adapter, I had the following observation.  I enabled two VFs by passing 'max_vfs=2' to ixgbe driver. One of the VFs was assigned to a guest.
In the guest, the ifconfig and ip tools reported 'RX packets' and 'TX packets' as zero, after pinging to a remote host. Looking into it further, the commit 4197aa7bb81877ebb06e4f2cc1b5fea2da23a7bd implements 64 bit per ring statistics. It seemed like the 'total_bytes' and 'total_packets' of RX and TX ring were being reset to zero by the RX and TX interrupt handlers, resulting in the user space tools reporting zero RX and TX bytes. 

The attached patch addresses the issue by preventing the resetting of RX and TX ring statistics to zero. The patch was taken against latest mainline 3.5-rc6 kernel.

I tested the patch by pinging  from the guest OS to a remote host.

ping -f <remote host> -c 10000

The ip and ifcofig showed the statistics increased by 10000 packets.  

# lspci | grep 82599
04:00.0 Ethernet controller: Intel Corporation 82599EB 10-Gigabit SFP+ Network Connection (rev 01)
04:00.1 Ethernet controller: Intel Corporation 82599EB 10-Gigabit SFP+ Network Connection (rev 01)
04:10.0 Ethernet controller: Intel Corporation 82599 Ethernet Controller Virtual Function (rev 01)
04:10.1 Ethernet controller: Intel Corporation 82599 Ethernet Controller Virtual Function (rev 01)
04:10.2 Ethernet controller: Intel Corporation 82599 Ethernet Controller Virtual Function (rev 01)
04:10.3 Ethernet controller: Intel Corporation 82599 Ethernet Controller Virtual Function (rev 01)

# lspci -s 04:00.0 -n
04:00.0 0200: 8086:154d (rev 01)
# lspci -s 04:10.0 -n
04:10.0 0200: 8086:10ed (rev 01) 

Please let me know if additional details and logs are required. 

With regards,
Narendra K

Download attachment "0001-ixgbevf-Prevent-RX-TX-statistics-getting-reset-to-ze.patch" of type "application/octet-stream" (2033 bytes)