On 11/16/2012 04:30 PM, Mathieu Desnoyers wrote: > * David Goulet ([email protected]) wrote: >> Hi Paul, >> >> The problem here would be that metadata can grow arbitrarily over time >> when let say new events are enabled during tracing or a new lib is >> dynamically loaded in the application you are tracing. Same goes for the >> kernel for loaded module or CPU hotplug... >> >> To achieve a static size of metadata during the whole life of a tracing >> session, I guess we need somekind of flag or option set to tell the >> tracers to just deny new events once started... which from there, we >> need Mathieu's opinion :) > > live support will eventually allow to side-track this whole issue by > flushing metadata to disk periodically during tracing,
Does that mean that the live tracing feature that currently lives in the lttngtop-live branch will go into lttng-tools and babeltrace any time soon ? Thanks Paul > > Thanks, > > Mathieu > >> >> Cheers! >> David >> >> Woegerer, Paul: >>> Hi, >>> >>> embedded users sometimes have to trace to tmpfs (e.g. streaming in not >>> an option due to missing network connectivity). >>> >>> Ramdisks of 16M to 128M size are created and as long as the ram disk >>> does not get full, tracing works fine. Unfortunately if the disk gets >>> full things fall apart: >>> >>> PERROR: Error in file write: No space left on device [in >>> lttng_consumer_on_read_subbuffer_mmap() at consumer.c:1367] >>> >>> The consumer daemon will not be able to write the metadata channel and >>> therefore the trace data set will be unusable (cannot be read with >>> babeltrace). >>> >>> -rwxrwxrwx 1 testuser users 0 Nov 16 11:22 metadata >>> -rwxrwxrwx 1 testuser users 15728640 Nov 16 11:22 myevents_0 >>> -rwxrwxrwx 1 testuser users 4096 Nov 16 11:22 myevents_1 >>> >>> Is it possible to somehow reserve the file size (fallocate) for metadata >>> so that in case the disk gets full at least the metadata gets written >>> and the resulting trace set is readable with babeltrace ? >>> >>> I wonder if that is possible at all. The consumer daemon doesn't know >>> upfront how much would need to be reserved for metadata, right ? >>> >>> Any ideas ? >>> >>> Thanks, >>> Paul >>> >>> >> >> _______________________________________________ >> lttng-dev mailing list >> [email protected] >> http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev > -- Paul Woegerer | SW Development Engineer http://go.mentor.com/sourceryanalyzer Mentor Embedded(tm) | Prinz Eugen Straße 72/2/4, Vienna, 1040 Austria Nucleus® | Linux® | Android(tm) | Services | UI | Multi-OS Android is a trademark of Google Inc. Use of this trademark is subject to Google Permissions. Linux is the registered trademark of Linus Torvalds in the U.S. and other countries. _______________________________________________ lttng-dev mailing list [email protected] http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
