This (current) behavior you describe is very suitable for our needs.

Is there an intention to insert a hook into setuid() in the future?
If yes - will the existing behavior remain as a default and the hook be 
used only if I choose to use it?

Thanks,

Amit Margalit
IBM XIV - Storage Reinvented
XIV-NAS Development Team
Tel. 03-689-7774
Fax. 03-689-7230



From:   Mathieu Desnoyers <[email protected]>
To:     Amit Margalit/Israel/IBM@IBMIL
Cc:     Michel Dagenais <[email protected]>, 
[email protected]
Date:   04/29/2013 07:27 PM
Subject:        Re: [lttng-dev] Is there a way to make LTTng use the same 
subbuffers for multiple processes?



* Amit Margalit ([email protected]) wrote:
> Another 2.2 question -
> 
> What if I have a single process, that forks, and each child process then 

> changes its own UID. Will the tracing continue on the parent UID 
buffers?

Yes, we indeed currently keep the user ID that was effective at process
creation or last exec() encountered, because we don't have hooks in
libc's setuid() at the moment.

Thanks,

Mathieu

> 
> Thanks,
> 
> Amit Margalit
> IBM XIV - Storage Reinvented
> XIV-NAS Development Team
> Tel. 03-689-7774
> Fax. 03-689-7230
> 
> 
> 
> From:   Michel Dagenais <[email protected]>
> To:     Amit Margalit/Israel/IBM@IBMIL
> Cc:     [email protected]
> Date:   04/29/2013 04:32 AM
> Subject:        Re: [lttng-dev] Is there a way to make LTTng use the 
same 
> subbuffers for multiple processes?
> 
> 
> 
> 
> > Our system is a 12-core x86 (6-core + HT). If I take 4 subbuffers of 
> 1MB, this means 4MB per
> > process. As the number of processes rises, this becomes prohibitive. 
> > For example, we may need to support > 500 sub-processes ==> 500 * 4MB 
= 
> 2GB - 
> > which is a bit too much.  Is there a way to tell LTTng to share the 
> sub-buffers with forked processes? 
> 
> This is the number one feature listed in the changelog for lttng-tools 
and 
> UST for version 2.2. The first release candidate is out so you can try 
the 
> feature, and the final 2.2 version should not be too far away.
> 
> http://lttng.org/lttng-tools-220-rc1
> - Add UST per UID buffers support
> 

> _______________________________________________
> lttng-dev mailing list
> [email protected]
> http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev


-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com


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