Messages in this thread | | | Date | Thu, 30 Apr 2009 10:45:29 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 00/19] tracing/workqueue: events support/enhancements, worklets tracing, fixes |
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* Frederic Weisbecker <fweisbec@gmail.com> wrote:
> Hi, > > This patchset brings various features for the workqueue tracer. > > The support of events tracing (tracepoint expanding): > - workqueue_creation > - workqueue_flush > - workqueue_destruction > > Also for the worklets: > - worklet_enqueue > - worklet_enqueue_delayed > - worklet_execute > - worklet_complete > - worklet_cancel > > Now, most of the lifecycle of worklets and workqueues is available. > > The histogram tracing now also supports the worklets. You can > measure the max and average execution time of a worklet. > > A good bunch of Oleg's comments have been addressed, at least the > critical ones (races which can cause freed pointer dereferences, memory > leak, etc...). The rest is more about the design itself, such as using > the workqueue as the identifier instead of the thread and other things > that are in discussion. > > Thanks! > > Frederic. > > The following changes since commit a0e39ed378fb6ba916522764cd508fa7d42ad495: > Heiko Carstens (1): > tracing: fix build failure on s390 > > are available in the git repository at: > > git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git tracing/workqueue > > Frederic Weisbecker (6): > tracing/workqueue: turn cpu_workqueue_stats::inserted into unsigned int > tracing/workqueue: add execution time average column > tracing/workqueue: add open/release file handlers > tracing/workqueue: defer workqueue stat release if needed > tracing/workqueue: use the original cpu affinity on probe_workqueue_destruction > tracing/workqueue: provide documentation for the workqueue tracer > > KOSAKI Motohiro (2): > workqueue_tracepoint: introduce workqueue_handler_exit tracepoint and rename workqueue_execution to workqueue_handler_entry > tracing/workqueue: add max execution time mesurement for per worklet > > Zhaolei (11): > ftrace, workqueuetrace: make workqueue tracepoints use TRACE_EVENT macro > trace_workqueue: use list_for_each_entry() instead of list_for_each_entry_safe() > trace_workqueue: remove cpu_workqueue_stats->first_entry > trace_workqueue: remove blank line between each cpu > trace_workqueue: add worklet information > workqueue_tracepoint: add workqueue_flush and worklet_cancel tracepoint > workqueue_tracepoint: change tracepoint name to fit worklet and workqueue lifecycle > workqueue_trace: separate worklet_insertion into worklet_enqueue and worklet_enqueue_delayed > tracing/workqueue: turn workfunc_stats::inserted into unsigned int > tracing/workqueue: avoid accessing task_struct's member variable in stat file read > tracing/workqueue: use list_for_each_entry instead of list_for_each_entry_safe in probe_workqueue_destruction() > > Documentation/trace/workqueue.txt | 114 ++++++++++ > include/trace/events/workqueue.h | 200 +++++++++++++++++ > include/trace/workqueue.h | 25 -- > kernel/trace/trace_stat.c | 8 + > kernel/trace/trace_stat.h | 3 + > kernel/trace/trace_workqueue.c | 444 +++++++++++++++++++++++++++++-------- > kernel/workqueue.c | 45 +++-- > 7 files changed, 697 insertions(+), 142 deletions(-) > create mode 100644 Documentation/trace/workqueue.txt > create mode 100644 include/trace/events/workqueue.h > delete mode 100644 include/trace/workqueue.h
I think one worry here - and this mirrors some of Andrew's concerns - is the debug code to instrumented code ratio. There's 500 lines of instrumentation for 1000 lines of code.
Is there a chance we can reduce that ratio, by factoring out bits of kernel/trace/trace_workqueue.c and perhaps compressing include/trace/events/workqueue.h some more?
Also, it would be nice to check how intuitive it is to visualize workqueue related details using the user-space ftrace-analyzer tool.
Kernel developers are one thing - but most of the Linux developers are user-space developers so any workqueue tracing details have to be intuitive (and useful) to them. (even though workqueues are a fundamentally in-kernel abstraction)
Ingo
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