Re: [Xen-devel] [PATCH v5 08/24] libxl: introduce libxl__vnuma_config_check

[Elena Ufimtseva <ufimtseva@xxxxxxxxx>]

On Fri, Feb 13, 2015 at 10:12 AM, Wei Liu <wei.liu2@xxxxxxxxxx> wrote:
> On Fri, Feb 13, 2015 at 02:15:47PM +0000, Ian Jackson wrote:
>> Wei Liu writes ("[PATCH v5 08/24] libxl: introduce 
>> libxl__vnuma_config_check"):
>> > This function is used to check whether vNUMA configuration (be it
>> > auto-generated or supplied by user) is valid.
>>
>> This looks plausible, but I think you should explain what the impact
>> of this patch is.  Presumably the intent is to replace various later
>> failures with ERROR_FAIL with something more useful and more
>> specific ?
>>
>
> Yes, providing more useful error message is on aspect. Another aspect is
> just to do sanity check -- passing an invalid layout to guest doesn't
> make much sense.
>
>> Are there any cases which this new check forbids but which are
>> currently accepted by libxl ?  If so then we have to think about
>> compatibility.
>>
>
> First thing is there is no previous supported vNUMA interface in
> toolstack so there won't be a situation where previous good config
> doesn't pass this check.
>
> Second thing is if user supplies a config without vNUMA configuration
> this function will not get called, so it won't have any effect.
>
>> Also I would like to see an ack from the authors of the vnuma support,
>> as I'm not familiar enough with vnuma to fully understand the
>> semantics of the new checks.
>>
>
> Elena and Dario, what do you think?

The checks themselves look reasonable. And unforgiving :)
I think we had discussion before and some previous patches were
bailing out to some default/basic vnuma
configuration (when possible) in case of 'recoverable'  errors in config.

Any sanity checks for distances?

>
> Wei.
>
>> Thanks,
>> Ian.



-- 
Elena

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