[ltt-dev] UST use case: Tracing QEMU/KVM

[pierre-marc.fournier@polymtl.ca (Pierre-Marc Fournier)]

Stefan Hajnoczi wrote:
> On Wed, May 26, 2010 at 11:46 PM, Pierre-Marc Fournier
> <pierre-marc.fournier at polymtl.ca> wrote:
>>> For large programs or programs that closely manage resources, a
>>> documented list of resources that libust uses would be useful.  This
>>> information can be used to understand whether libust might interfere
>>> with the program being traced.  For example, will heap allocations be
>>> made after startup?  Will file descriptors be held open?  The listener
>>> thread?
>> Currently, ust is designed to be transparent to the running process in most
>> cases. However, if your program makes very unusual assumptions about the
>> usage of some resources, this could result in a conflict.
>>
>> - Yes, heap allocations can be made after startup.
>> - Sockets will definitely be kept open by the listener thread.
>> - Currently, I don't think any file descriptors are kept open, but it could
>> be the case in the future.
>> - SystemV shared memory segments are mapped in the address space.
>> - A listener thread is always started to wait for connections from ustctl or
>> ustd.
>>
>> If you feel it would be important to avoid some of these things, please let
>> me know.
> 
> Thanks for explaining, sounds fine to me.  If you want to add this as
> an appendix to the documentation I think it is useful information for
> an application developer who wants to integrate UST support.
> 

Just added a section (8) about this in the manual.

Thanks.

pmf