On Wed, Nov 3, 2010 at 11:13 PM, Mathieu Desnoyers <[email protected]> wrote: > * Sam Liao ([email protected]) wrote: >> Hi, >> >> I'm trying to combine the kernel trace and userspace trace, and it >> seems that the >> the userspace events can not be recognized to the right process with the >> kernel >> events. I'm not sure if this is a problem of timestamp between kernel >> and userspace. >> >> Here is the environment I'm using: >> ---- >> Linux Trace Toolkit Visualizer 0.12.35-20082010 >> linux kernel 2.6.34.6 >> ust-0.4. ( I update the clock to use clock_gettime). > > If you are on x86 or powerpc, using the clock source that does not use > clock_gettime would directly read the timestamp counter value, which > should work. Make sure your architecture (on x86) has synchronized > contant TSCs. LTTng complains about using a work-around in dmesg if it > is not the case. If lttng uses the workaround on x86, then there is > currently no mean to gather synchronized ust-lttng traces. As Julien > said, we're currently working on a vdso solution to make this all work. >
Thanks, after apply with the "rdtsc" clock source and set up the correct clock frequency, the kernel trace and ust trace seems to be consistent now. Thanks, -Sam > Thanks, > > Mathieu > >> ---- >> >> Is there anything I missed? Also I'm thinking about one problem, if >> ust using clock_gettime to >> get the nonseconds timestamp which is actually the timestamp that the user >> application is doing the clock_gettime system call instead the >> userspace event, how ust >> deal with such difference and get this fixed when trace combination? >> >> Thanks, >> -Sam >> >> _______________________________________________ >> ltt-dev mailing list >> [email protected] >> http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev >> > > -- > Mathieu Desnoyers > Operating System Efficiency R&D Consultant > EfficiOS Inc. > http://www.efficios.com > _______________________________________________ ltt-dev mailing list [email protected] http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
