Re: [PATCH v2 2/2] crypto: qat - Enforce valid numa configuration

[Tadeusz Struk <tadeusz.struk@intel.com>]

On 10/14/2014 03:53 AM, Prarit Bhargava wrote:
>>
>> -	node = adf_get_dev_node_id(pdev);
>> -	accel_dev = kzalloc_node(sizeof(*accel_dev), GFP_KERNEL, node);
>> +	if (num_possible_nodes() > 1 && dev_to_node(&pdev->dev) < 0) {
>> +		/* If the accelerator is connected to a node with no memory
>> +		 * there is no point in using the accelerator since the remote
>> +		 * memory transaction will be very slow. */
>> +		dev_err(&pdev->dev, "Invalid NUMA configuration.\n");
> 
> This is a lot better.  Thank you for taking my comments into account here.

Thanks for taking the time to review my patch and providing your comments.

> 
> Let's say I have a non-functional qat device and I see the above message in
> the boot log.  The log doesn't say what to do ... so perhaps change it to
> 
> 	dev_err(&pdev->dev, FW_BUG "numa node is set to %d.  This can be overridden by
> using the numa_node module parameter.",
> 	        dev_to_node(&pdev->dev));
> 
> and add a numa_node module parameter to let the user set that at module load
> time in case their FW is broken?  I've found that sysadmins are knowledgeable
> about these types of things these days and are more than capable of looking
> at sysfs and numactl to determine where a device is.
> 

But then what if there are two devices and each belongs to different
node. In this case we would fix one and break the other. I think if the
FW is broken then using on core encryption will be safer. If a sysadmins
is really knowledgeable, then she or he can change the code to customize
it for a given platform and rebuild the module.
Other than that as far as I know module parameters are not encouraged.
T