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

[Shailabh Nagar <nagar@watson.ibm.com>]

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,
rather than risk delaying exits ? The cases where exits are so frequent 
as in this program should be
very few. Making the reception privileged would kind of constrain the 
utilization of stats and I'm not
sure if  its warranted.


--Shailabh