Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats

Jay Lan
2006-06-21T21:45:00Z

Shailabh Nagar wrote:
> Andrew Morton wrote:
>
>> On Wed, 21 Jun 2006 12:11:13 -0700
>> Jay Lan <jlan@engr.sgi.com> wrote:
>>
>>
>>
>>> Another observation that i considered bad news is that all
>>> 10 runs produced 1 to 5 recv() error with errno=105 (ENOBUF).
>>>
>>
>> Well that's rather bad. AFAICT most of the allocations in there are
>> GFP_KERNEL, so why is this happening?
>>
>>
>
> Need to trace the cause.
>
>> Because the kernel is producing netlink messages faster than
>> userspace can
>> consume them, perhaps?
> Hmm...possible. A quick check would be to reduce the frequency of
> exits and see.
>
>> If so, the sender needs to block, which means we
>> need to make reception of these stats a privileged operation?
>>
>>
> Won't it suffice to make delivery of these stats best effort, with
> userspace dealing with missing data,

How do you recover the missed data?

> rather than risk delaying exits ? The cases where exits are so
> frequent as in this program should be

This is very true. However, it was a 2p IA64 machine. I am too frightened to
speak "512p"...

Regards,
- jay

> very few. Making the reception privileged would kind of constrain the
> utilization of stats and I'm not
> sure if its warranted.
>
>
> --Shailabh
>
>