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

[<Narendra_K@Dell.com>]

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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




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From 37b3c2d1b7a1f5d45566b22fbaa038b3e5ed3218 Mon Sep 17 00:00:00 2001
From: Narendra K <narendra_k@dell.com>
Date: Thu, 12 Jul 2012 18:20:55 +0530
Subject: [PATCH] ixgbevf - Prevent RX/TX statistics getting reset to zero

The commit 4197aa7bb81877ebb06e4f2cc1b5fea2da23a7bd implements 64 bit
per ring statistics. But the driver resets the 'total_bytes' and
'total_packets' from RX and TX rings in the RX and TX interrupt
handlers to zero. This results in statistics being lost and user space
reporting RX and TX statistics as zero. This patch addresses the
issue by preventing the resetting of RX and TX ring statistics to
zero.

Signed-off-by: Narendra K <narendra_k@dell.com>
---
 drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c |   12 ------------
 1 file changed, 12 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
index f69ec42..8b304a4 100644
--- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
+++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
@@ -969,8 +969,6 @@ static irqreturn_t ixgbevf_msix_clean_tx(int irq, void *data)
 	r_idx = find_first_bit(q_vector->txr_idx, adapter->num_tx_queues);
 	for (i = 0; i < q_vector->txr_count; i++) {
 		tx_ring = &(adapter->tx_ring[r_idx]);
-		tx_ring->total_bytes = 0;
-		tx_ring->total_packets = 0;
 		ixgbevf_clean_tx_irq(adapter, tx_ring);
 		r_idx = find_next_bit(q_vector->txr_idx, adapter->num_tx_queues,
 				      r_idx + 1);
@@ -994,16 +992,6 @@ static irqreturn_t ixgbevf_msix_clean_rx(int irq, void *data)
 	struct ixgbe_hw *hw = &adapter->hw;
 	struct ixgbevf_ring  *rx_ring;
 	int r_idx;
-	int i;
-
-	r_idx = find_first_bit(q_vector->rxr_idx, adapter->num_rx_queues);
-	for (i = 0; i < q_vector->rxr_count; i++) {
-		rx_ring = &(adapter->rx_ring[r_idx]);
-		rx_ring->total_bytes = 0;
-		rx_ring->total_packets = 0;
-		r_idx = find_next_bit(q_vector->rxr_idx, adapter->num_rx_queues,
-				      r_idx + 1);
-	}
 
 	if (!q_vector->rxr_count)
 		return IRQ_HANDLED;
-- 
1.7.10.1