3ware RAID ctrlr: twe0: twe_map_request: malloc failed.

[Howard Goldstein]

Scott Long wrote:
> Howard Goldstein wrote:
>> Would someone confirm (or disabuse!) me of the belief that these 3ware
>> Escalade 8106-LP2 (2 port sata raid controllers) related messages are
>> informational and the UFS device is retrying after it sees ENOMEM
>> causing these?
>>
>> Aug 13 10:29:48 cally kernel: twe0: twe_map_request: malloc failed
>> Aug 13 10:33:04 cally kernel: twe0: twe_map_request: malloc failed
>> Aug 13 11:05:37 cally kernel: twe0: twe_map_request: malloc failed
>> Aug 13 11:14:55 cally kernel: twe0: twe_map_request: malloc failed
>> Aug 13 12:07:44 cally kernel: twe0: twe_map_request: malloc failed
>> Aug 13 12:28:05 cally kernel: twe0: twe_map_request: malloc failed
>> Aug 13 14:29:59 cally kernel: twe0: twe_map_request: malloc failed
>>
>> (Either way but particularly in the event the data are being lost is
>> there a sysctl or kernel build option to supply a bit more memory in
>> advance?)
> 
> The system is doing unaligned I/O to the array (either via an app that
> has a file opened O_DIRECT, or via I/O directly to the device node), and
> there is corresponding memory pressure that is making the driver fail
> at the re-alignment process.  The problem is likely temporary and the
> operation eventually succeeds after a few retries, but success is not
> guaranteed, and failure will almost certainly cause system instability.
> The fix is to rewrite the alignment code in the driver to use the
> automatic, failure-free, alignment service that busdma provides.  I'm
> happy to provide direction to anyone who wants to tackle this.

Alright, I like this idea since rebuilding the devices to avoid what I
thought were unaligned access didn't work and I'm still seeing these
messages and a performance hit I don't understand.  I imagine I'll get
better performance too if the driver can avoid doing its own alignment
which probably isn't as optmized (?)  The busdma man page looks nice and
complete too - cool

Could you point me to a model driver or two already using the busdma stuff?