Re: megasas stops I/O when running kernel as dom0 under xen4.1/4.2

[Andreas Olsowski <andreas.olsowski@leuphana.de>]

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Am 19.08.2011 14:28, schrieb Andrew Cooper:
> On 15/08/11 13:52, Andreas Olsowski wrote:
>> On 08/15/2011 12:49 PM, Simon Rowe wrote:
>>> I've found adding
>>>
>>> 	options megaraid_sas poll_mode_io=1
>>>
>>> makes both of the systems we're seeing this on stable.
>> ive been told to try that one and it works for me too (been running test
>> io for roughly 5 minutes now).
>>
>> driver version
>> megasas: 00.00.05.30 Tue. Jan. 4 17:00:00 PDT 2011
>
> Hello - I am now debugging.
>
> It seems that the megaraid_sas driver will try and use either MSI-X or
> legacy PCI interrupts mode, but will never try to use MSI.  The box we
> can reproduce the problem on has MSI support but not MSI-X support.
>
> As an experiment, I put a single call to pci_enable_msi() in the
> megasas_probe_one() function, immediately after pci_set_master().  I now
> cannot reproduce the problem.
>
> Do any of the boxes you have which reproduce the problem set up MSI-X
> interrupts for the megasas driver, or are they all using legacy PCI
> interrupts?
>
> (I am also emailing an LSI contact asking why they do not use MSI
> interrupts)
>
> ~Andrew
>

No the affected systems DO NOT use MSI-X

Below is output from 3 Servers, xenturio1 and tarballerina are affected 
(same old raid controller) whereas netcatarina is not (newer raid 
controller).

May i add, the 1078 series raid controller isnt listed on the LSI 
homepage, the 9260 is.

The affected servers are Dell PE2950 and R710.
Unaffectes is are the R610s.

Hope this helps, below is some output of the servers:


root@xenturio1:~# cat /proc/interrupts  |grep mega
   16:       2545          0          0          0          0          0 
          0          0  xen-pirq-ioapic-level  megasas
root@xenturio1:~# lspci |grep LSI
01:00.0 RAID bus controller: LSI Logic / Symbios Logic MegaRAID SAS 1078 
(rev 04)


root@tarballerina:~# cat /proc/interrupts  |grep mega
   33:      47264          0          0          0          0          0 
          0          0  xen-pirq-ioapic-level  megasas
root@tarballerina:~# lspci |grep LSI
03:00.0 RAID bus controller: LSI Logic / Symbios Logic MegaRAID SAS 1078 
(rev 04)


root@netcatarina:~# cat /proc/interrupts  |grep mega
2237:      88684          0          0          0          0          0 
          0          0  xen-pirq-msi-x     megasas
root@netcatarina:~# lspci |grep LSI
03:00.0 RAID bus controller: LSI Logic / Symbios Logic LSI MegaSAS 9260 
(rev 05)



-- 
Andreas Olsowski
Leuphana Universität Lüneburg
Rechen- und Medienzentrum
Scharnhorststraße 1, C7.015
21335 Lüneburg

Tel: ++49 4131 677 1309


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