lkml.org 
[lkml]   [2010]   [Apr]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 00/10][RFC] tracing: Lowering the footprint of TRACE_EVENTs
* 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


\
 
 \ /
  Last update: 2010-04-28 22:21    [W:0.278 / U:0.344 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site