[lttng-dev] [RELEASE] LTTng Tools 2.2.0 - Cuda (STABLE)

[Mathieu Desnoyers]

* Thibault, Daniel (Daniel.Thibault at drdc-rddc.gc.ca) wrote:
> -----Message d'origine-----
> Per UID buffers makes every application sharing the same UID to use the same buffers.
> [...]
> Also, the buffers for UST application are now created in the consumer and passed to the application. Thus, the buffer ownership has been transfered from the UST tracer to the consumer.
> -----Fin du message d'origine-----
> 
>    So what David really meant was:
> 
> Also, the per-PID buffers for UST application are now created in the consumer and passed to the application. Thus, the buffer ownership has been transferred from the UST tracer to the consumer in the per-PID case.

yes

> 
>    And I presume the per-UID buffers remain owned by the user-space-servicing root consumer daemon?

yes, or whichever consumer daemon is used (e.g. per-user daemon if
sessiond is run as a simple user rather than as root)

>    When lttng is being run as an unprivileged user (and can thus trace
>    only user-space), setting the buffering scheme to per-UID would
>    mean the trace uid folder would have just one subfolder, the
>    unprivileged user's uid (e.g.
>    $HOME/lttng-traces/session-20130611-1223344/ust/uid/1000/64-bit),
>    right? 

yes

> I also presume the uid used is the real uid (ruid)?

yes, this is correct. The one returned by getuid().

Thanks,

Mathieu

> 
> Daniel U. Thibault
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-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com