Re: taskstats interface for accounting

[Jay Lan <jlan@engr.sgi.com>]

Shailabh Nagar wrote:
> Jay Lan wrote:
>
>> Hi Balbir and Shailabh,
>>
>> I finally have time to think about implementation details of CSA over
>> taskstats interface. I took another look at the taskstats interface
>> proposal and was a little bit nervous.
>>
>> Do you remember i suggested to use #ifdef to cut down traffic and i
>> was told a generic netlink header would serve the purpose?
>> What i see now at Documentation/accounting/taskstats.txt saying
>> NETLINK_GENERIC family is used for unicast query/reply mode. The
>> NETLINK_GENERIC family provides great flexsibility on what to
>> receive. However, CSA only uses the multicast mode to receive from
>> kernel
>> whenever tasks are existing. I guess i would need to read the netlink
>> documentation more carefully to see whether my understanding is
>> correct.
>
> I don't think there's a problem here. The netlink socket opened for
> listening to
> taskstat data sent on task exit can be done in multicast mode....the
> example code in the
> Documentation does that.
>
>>
>> Another thing i overlooked when i did the review was that taskstats
>> interface is designed to provide _BOTH_ per task _AND_ per thread
>> accounting data EVERY TIME a task exists. A thread is an aggregate
>> of (per-pid) tasks. Since this type of aggregation is not used in
>> CSA, half of data traffic would be useless. Can we add a way to
>> configure to not send per-thread data to the socket?
>
> I don't see why not. We could extend the command set to set tgid
> sending on/off.

This would be great!

But, we can have a number of applications listening on the socket. We
surely do not want applications to send conflicting commands to the kernel.
Maybe we can make it a /etc/sysconfig option.

Regards,
 - jay

>
> Regards,
> Shailabh
>
>> Regards,
>> jay
>
>