Messages in this thread | | | Date | Wed, 28 Apr 2010 16:18:04 -0400 | From | Mathieu Desnoyers <> | Subject | Re: [PATCH 00/10][RFC] tracing: Lowering the footprint of TRACE_EVENTs |
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* Steven Rostedt (rostedt@goodmis.org) wrote: > This is an RFC patch set that also affects kprobes and perf.
Hi Steven,
> > At the Linux Collaboration Summit, I talked with Mathieu and others about > lowering the footprint of trace events. I spent all of last week > trying to get the size as small as I could. > > Currently, each TRACE_EVENT() macro adds 1 - 5K per tracepoint. I got various > results by adding a TRACE_EVENT() with the compiler, depending on > config options that did not seem related. The new tracepoint I added > would add between 1 and 5K, but I did not investigate enough to > see what the true size was.
Adding only one might not give an accurate picture, as some sections can be aligned on 4k boundaries. So if the added TRACE_EVENT() brings you to the next 4k page, your added size is bumped of an extra 4k.
> > What was consistent, was the DEFINE_EVENT(). Currently, it adds > a little over 700 bytes per DEFINE_EVENT(). > > This patch series does not seem to affect TRACE_EVENT() much (had > the same various sizes), but consistently brings DEFINE_EVENT()s > down from 700 bytes to 250 bytes per DEFINE_EVENT(). Since syscalls > use one "class" and are equivalent to DEFINE_EVENT() this can > be a significant savings. > > With events and syscalls (82 events and 616 syscalls), before this > patch series, the size of vmlinux was: 16161794, and afterward: 16058182. > > That is 103,612 bytes in savings! (over 100K) > > > Without tracing syscalls (82 events), it brought the size of vmlinux > down from 1591046 to 15999394.
Probably a cut n paste error on the line above. Should read:
down from 16021465 to 15999394.
if you want the "22071 bytes in savings" to hold.
Will look over your patchset.
Thanks,
Mathieu
> > 22,071 bytes in savings. > > This is just an RFC (for now), to get peoples opinions on the changes. > It does a bit of rewriting of the CPP macros, just to warning you ;-) > > -- Steve > > The code can be found at: > > git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git > tip/tracing/rfc-1 > > > Steven Rostedt (10): > tracing: Create class struct for events > tracing: Let tracepoints have data passed to tracepoint callbacks > tracing: Convert TRACE_EVENT() to use the DECLARE_TRACE_DATA() > tracing: Remove per event trace registering > tracing: Move fields from event to class structure > tracing: Move raw_init from events to class > tracing: Allow events to share their print functions > tracing: Move print functions into event class > tracing: Remove duplicate id information in event structure > tracing: Combine event filter_active and enable into single flags field > > ---- > include/linux/ftrace_event.h | 71 +++++++++--- > include/linux/syscalls.h | 55 +++------- > include/linux/tracepoint.h | 119 ++++++++++++++++--- > include/trace/ftrace.h | 215 ++++++++++------------------------ > include/trace/syscall.h | 9 +- > kernel/trace/blktrace.c | 13 ++- > kernel/trace/kmemtrace.c | 28 +++-- > kernel/trace/trace.c | 9 +- > kernel/trace/trace.h | 5 +- > kernel/trace/trace_event_perf.c | 17 ++- > kernel/trace/trace_events.c | 126 +++++++++++++------- > kernel/trace/trace_events_filter.c | 28 +++-- > kernel/trace/trace_export.c | 16 ++- > kernel/trace/trace_functions_graph.c | 2 +- > kernel/trace/trace_kprobe.c | 104 ++++++++++------- > kernel/trace/trace_output.c | 137 +++++++++++++++------- > kernel/trace/trace_output.h | 2 +- > kernel/trace/trace_syscalls.c | 105 +++++++++++++++-- > kernel/tracepoint.c | 91 ++++++++------- > 19 files changed, 700 insertions(+), 452 deletions(-) >
-- Mathieu Desnoyers Operating System Efficiency R&D Consultant EfficiOS Inc. http://www.efficios.com
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