netdev - RE: Low performance Intel 10GE NIC (3.2.10) on 2.6.38 Kernel

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Date:	Tue, 12 Apr 2011 12:40:06 +0800
From:	Wei Gu <wei.gu@...csson.com>
To:	Eric Dumazet <eric.dumazet@...il.com>,
	Alexander Duyck <alexander.h.duyck@...el.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
CC:	netdev <netdev@...r.kernel.org>,
	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>
Subject: RE: Low performance Intel 10GE NIC (3.2.10) on 2.6.38 Kernel

Hi,
I found the problem was introduced by this revert patch "2010-08-13     Peter Zijlstra  sched: Revert nohz_ratelimit() for now"

I tried the remove this patch from 2.6.35.2 and then build the application again, then the ixgbe driver looks works fine.
I don't know why this time revert the  nohz_ratelimit() will cause the problem on ixgbe driver, since this  nohz_ratelimit was first introduced "2010-03-11". And before that time with 2.6.32 kernel it also doesn't have this problem with ixgbe driver.


Some log from git:
=========================================================================================
2.6.35.2
2010-08-13      Peter Zijlstra  sched: Revert nohz_ratelimit() for now
2.6.35.1
2010-08-01      Linus Torvalds  Linux 2.6.35 v2.6.35
2010-06-17      Peter Zijlstra  nohz: Fix nohz ratelimit
2.6.35-rc3
2010-03-11      Mike Galbraith  sched: Rate-limit nohz

Thanks
WeiGu

-----Original Message-----
From: Wei Gu
Sent: Tuesday, April 12, 2011 9:23 AM
To: 'Eric Dumazet'
Cc: Alexander Duyck; netdev; Kirsher, Jeffrey T
Subject: RE: Low performance Intel 10GE NIC (3.2.10) on 2.6.38 Kernel

I was not stress the NIC/CPU, since I only send 290Kpps 400byte packets towards eth10. the CPU load almost 100%IDEL.

BTW, there are some problem with perf tool on 2.6.35.2, I will try to get you the top offenders if possible.

Thanks
WeiGu

-----Original Message-----
From: Eric Dumazet [mailto:eric.dumazet@...il.com]
Sent: Monday, April 11, 2011 11:43 PM
To: Wei Gu
Cc: Alexander Duyck; netdev; Kirsher, Jeffrey T
Subject: RE: Low performance Intel 10GE NIC (3.2.10) on 2.6.38 Kernel

Le lundi 11 avril 2011 à 23:14 +0800, Wei Gu a écrit :
> I tried the ixgbe-3.3.8 (insmod ixgbe.ko RSS=8,8,8,8,8,8,8,8 FdirMode=0,0,0,0,0,0,0,0 Node=0,0,1,1,2,2,3,3)  from e1000.sf.net both on 2.6.35.1 and 2.6.35.2, same observation as 3.2.10 ixgbe driver, On 2.6.35.2 it have high rx errors:
> Ethtool -S eth10 |grep error
>      rx_errors: 0
>      tx_errors: 0
>      rx_over_errors: 0
>      rx_crc_errors: 0
>      rx_frame_errors: 0
>      rx_fifo_errors: 0
>      rx_missed_errors: 2263088
>      tx_aborted_errors: 0
>      tx_carrier_errors: 0
>      tx_fifo_errors: 0
>      tx_heartbeat_errors: 0
>      rx_long_length_errors: 0
>      rx_short_length_errors: 0
>      rx_csum_offload_errors: 0
>      fcoe_last_errors: 0
>

It would be nice you post perf record / perf report results

During your stress , do

perf record -a -g sleep 10
perf report

And post "top offenders"

Thanks


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