Date:	Wed, 21 Jan 2009 14:51:07 -0800
From:	"Duyck, Alexander H" <alexander.h.duyck@...el.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>, Ingo Molnar <mingo@...e.hu>
CC:	"Waskiewicz Jr, Peter P" <peter.p.waskiewicz.jr@...el.com>,
	"Allan, Bruce W" <bruce.w.allan@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
	"Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
	"e1000-devel@...ts.sourceforge.net" 
	<e1000-devel@...ts.sourceforge.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: igb regression (interface hang) with latest -git

Rafael J. Wysocki wrote:
> On Wednesday 21 January 2009, Ingo Molnar wrote:
>> 
>> * Rafael J. Wysocki <rjw@...k.pl> wrote:
>> 
>>> On Wednesday 21 January 2009, Ingo Molnar wrote:
>>>> 
>>>> * Ingo Molnar <mingo@...e.hu> wrote:
>>>> 
>>>>>> One other piece of info (in addition to what Bruce requested)
>>>>>> that would be useful is after you've done ifconfig eht0 up, cat
>>>>>> /proc/interrupts | grep eth0 and send that output (I want to see
>>>>>> your MSI-X configuration).
>>>>> 
>>>>> here it is:
>>>>> 
>>>>>  79:         35          0       9836       7451       1197      
>>>>>  1360        766          0       2196        995        770     
>>>>>  0       2051        863       4714       1879   PCI-MSI-edge    
>>>>>  eth0-tx-0 80:       2335          0       2718       3651      
>>>>>  5024       9850        533          0       1405       1095     
>>>>>  0          0       4421       1229          0       2002  
>>>>>  PCI-MSI-edge      eth0-tx-1 81:         33          0          0
>>>>>  5478       1125       6585       4865       6306          0     
>>>>>  0          0        714       3757          0       2662      
>>>>> 1020   PCI-MSI-edge      eth0-tx-2 82:         21       1428     
>>>>> 3136       3783       4249       6833          0          0      
>>>>> 4175          0          0       1465       1940       1780      
>>>>> 6286          0   PCI-MSI-edge      eth0-tx-3 83:         40     
>>>>> 0          0       4788          0       1486          0      
>>>>> 7185       3998       8637       1409       6785          0      
>>>>> 0          0      10060   PCI-MSI-edge      eth0-rx-0 84:        
>>>>> 70       1441       2606       1342          0       1678      
>>>>> 4301       1839          0       6507       6910      16470      
>>>>> 0       1484       1004          0   PCI-MSI-edge      eth0-rx-1
>>>>> 85:         40       1368          0       3560       5022      
>>>>> 2040          5       1719          0       2037        956      
>>>>> 40          0      17264       6456       2833   PCI-MSI-edge    
>>>>> eth0-rx-2 86:         44        414          5       1164        
>>>>> 30       4513       4595       1542          0      10033      
>>>>> 1151          0       4961       4203          0      10703  
>>>>> PCI-MSI-edge      eth0-rx-3 87:          1          0          0 
>>>>> 0          0          0          0          0          0         
>>>>> 0          0          0          0          0          0         
>>>>> 0   PCI-MSI-edge      eth0                    
>>>> 
>>>> btw., i turned off CONFIG_PCI_MSI and that worked around the
>>>> interface 
>>>> hang - the box has 40 minutes uptime now and still no hang. (it
>>>> would hang 
>>>> within 5 minutes previously)
>>>> 
>>>> can test the revert of any of these commits:
>>>> 
>>>> e42e4ba: igb: fix anoying type mismatch warning on rx/tx queue
>>>> sizing 8d25332: igb: Fix build warning when DCA is disabled.
>>>> 26bc19e: igb: re-order queues to support cleaner use of ivar on
>>>> 82576 0e014cb: igb: defeature tx head writeback
>>>> 678c610: drivers/net/igb: remove dead code (function
>>>> 'igb_read_pci_cfg') 908a7a1: net: Remove unused netdev arg from
>>>> some NAPI interfaces. 
>>>> ea943d4: igb: fixup AER with proper error handling
>>>> 5e8427e: igb: Correctly determine pci-e function number in virtual
>>>> environment 
>>>> b4557be: igb: update handling of RCTL for smaller buffer sizes
>>>> cb7b48f: igb/e1000e: Naming interrupt vectors
>>>> 40a914f: igb: Add support for pci-e Advanced Error Reporting
>>>> 527d47c: igb: link up/down messages must follow a specific format
>>>> 5b9ab2e: Merge branch 'master' of
>>>> master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 69d728b:
>>>> igb: loopback bits not correctly cleared from RCTL register
>>>> 9b07f3d: igb: remove unneeded bit refrence when enabling jumbo
>>>> frames  
>>>> f5f4cf0: igb: do not use phy ops in ethtool test cleanup for
>>>> non-copper parts 0082982: netdev: add more functions to netdevice
>>>> ops 68fd991: igb: Fix tx/rx_ring_count parameters for igb on
>>>> suspend/resume/ring resize b2d5653: igb: simplify swap in
>>>> clean_rx_irq if using packet split 2e5c692: igb: convert to
>>>> net_device_ops 198d6ba: Merge branch 'master' of
>>>> master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 4cf1653:
>>>> netdevice: safe convert to netdev_priv() #part-2 
>>>> babcda7: drivers/net: Kill now superfluous ->last_rx stores.
>>>> 7c510e4: net: convert more to %pM
>>>> 
>>>> i had a quick look at all of them but none seem to have a direct
>>>> connection to MSI-X interrupt generation.
>>>> 
>>>> There's a couple of ones that could have side effects:
>>>> 
>>>> Maybe this one:
>>>> 
>>>>   26bc19e: igb: re-order queues to support cleaner use of ivar on
>>>> 82576 
>>>> 
>>>> due to its sheer commit size and due to its impact on the hw
>>>> programming. 
>>>> 
>>>> or:
>>>> 
>>>>   0e014cb: igb: defeature tx head writeback
>>>> 
>>>> Might have some side-effect on tx-completion IRQs and might tickle
>>>> firmware bugs?
>>>> 
>>>> Or:
>>>> 
>>>>   5e8427e: igb: Correctly determine pci-e function number in
>>>> virtual environment 
>>>> 
>>>> while it should have no impact on a native kernel, it does change
>>>> the PCI 
>>>> config space access sequences.
>>>> 
>>>> Or maybe:
>>>> 
>>>>   69d728b: igb: loopback bits not correctly cleared from RCTL
>>>> register 
>>>> 
>>>> as this impacts the PCI programming too.
>>>> 
>>>> But ... i dont really know this code so i'm guessing around.
>>> 
>>> Well, AER (Advanced Error Reporting) is currently broken w/ MSI-X,
>>> so maybe this one: 
>>> 
>>> 40a914f: igb: Add support for pci-e Advanced Error Reporting
>> 
>> ah, yeah, that makes sense. I discarded that commit because i was
>> unsure whether this box has AER and the boot log said:
>> 
>>  calling  aer_service_init+0x0/0x20 @ 1
>>  initcall aer_service_init+0x0/0x20 returned 0 after 61 usecs
>> 
>> shouldnt it have printed something if AER was available?
> 
> The driver doesn't seem to print anything on success as far as I can
> see. It only reports faliures, apparently.
> 
> Thanks,
> Rafael

I have noticed that too after going through the logs on one of the Nahalem systems I have here.  It might just be best to disable AER in the kernel if it isn't functional on the system and see if that helps to clear up the issue.

I am leaning torward some external influence affecting the igb driver.  Of the changes I made the only one I could really think of that would have much affect on MSI-X interrupts would be queue reordering, but that should have little to no effect on 82575 parts as it was intended to only reorder queues on 82576, in addition I would expect an immediate issue since the configuration is pretty much static after the queues are allocated.  The only other patch that could even have a remote possiblity would be the TX head writeback defeature, but I would only expect that one to affect tx.

Thanks,

Alex

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