[openib-general] IB/mthca: question about HCA profile module parameters

[Moni Shoua]

Dotan Barak wrote:
> Hi Moni.
> 
> I tried to use the mthca module parameter: for example i tried to change
> the number of QPs.
> 
> I got several failures when i used the HCA 25204:
> * sometimes i got the following error message (when using big values,
> for example 512K QPs):
> ib_mthca: 0000:0c: INIT_HCA command failed aborting.
> ib_mthca: probe of 0000:0c: failed with error -16
> * when i tried to use small amount of QPs (1024) the machine just hanged
> and i noticed a kernel oops message on the console
> 
OK. So I ran more tests on my setup which now include
- Dual x86_64 processor (Intel Xeon)
- 1GB RAM
- 25204 HCA - fw_ver=1.1.0

In the range of 16K - to 256K of value for num_qp I got no errors.
For lower and higher values I got errors from INIT_HCA and (not always and just for very low values) a machine hung.
Do you have the Oops saved somewhere? Can you put it here please?


> 
> Did you verify the HCA profile module parameter feature?
As I mentioned earlier, I verified that non default values can be assigned 
and that the HCA works for some selected values. 
I also noticed that illegal cause the driver to throw a message to the kernel log.
However, I didn't test the exact behaviout of all possible values for each profile variable.
> Is there is any known limitation for the values that should be used?
> (for example: only values which are power of two)
> 
> 
I guess that it is clear that there are hardware limitations that don't allow setting of any value.
Unfotunately, even after looking for them in the PRM, I couldn't figure out which are they.
The software limits the value to be a power of 2 and corrects the users if they try to set a wrong value (to the nearest power of 2). In that case a warning message is thrown to the kernel log.
> thanks
> Dotan
>