From mboxrd@z Thu Jan 1 00:00:00 1970 From: pierre-marc.fournier@polymtl.ca (Pierre-Marc Fournier) Date: Thu, 27 May 2010 15:36:44 -0400 Subject: [ltt-dev] UST use case: Tracing QEMU/KVM In-Reply-To: References: <1274673453.6759.5.camel@Nokia-N900-42-11> <4BFDA4BE.4020400@polymtl.ca> Message-ID: <4BFEC9CC.50401@polymtl.ca> Stefan Hajnoczi wrote: > On Wed, May 26, 2010 at 11:46 PM, Pierre-Marc Fournier > 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