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

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 19/08/11 15:17, Andreas Olsowski wrote:
> 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)
>

This further confirms my findings.

Do you mind intserting a call to pci_enable_msi() in the probe function
and see if that sorts out your two problem cases?

-- 
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com