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authorLinus Torvalds <torvalds@linux-foundation.org>2014-08-04 11:50:00 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-08-04 11:50:00 -0700
commitb8c0aa46b3e86083721b57ed2eec6bd2c29ebfba (patch)
tree45e349bf8a14aa99279d323fdc515e849fd349f3 /Documentation/trace
parentc7ed326fa7cafb83ced5a8b02517a61672fe9e90 (diff)
parentdc6f03f26f570104a2bb03f9d1deb588026d7c75 (diff)
Merge tag 'trace-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt: "This pull request has a lot of work done. The main thing is the changes to the ftrace function callback infrastructure. It's introducing a way to allow different functions to call directly different trampolines instead of all calling the same "mcount" one. The only user of this for now is the function graph tracer, which always had a different trampoline, but the function tracer trampoline was called and did basically nothing, and then the function graph tracer trampoline was called. The difference now, is that the function graph tracer trampoline can be called directly if a function is only being traced by the function graph trampoline. If function tracing is also happening on the same function, the old way is still done. The accounting for this takes up more memory when function graph tracing is activated, as it needs to keep track of which functions it uses. I have a new way that wont take as much memory, but it's not ready yet for this merge window, and will have to wait for the next one. Another big change was the removal of the ftrace_start/stop() calls that were used by the suspend/resume code that stopped function tracing when entering into suspend and resume paths. The stop of ftrace was done because there was some function that would crash the system if one called smp_processor_id()! The stop/start was a big hammer to solve the issue at the time, which was when ftrace was first introduced into Linux. Now ftrace has better infrastructure to debug such issues, and I found the problem function and labeled it with "notrace" and function tracing can now safely be activated all the way down into the guts of suspend and resume Other changes include clean ups of uprobe code, clean up of the trace_seq() code, and other various small fixes and clean ups to ftrace and tracing" * tag 'trace-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (57 commits) ftrace: Add warning if tramp hash does not match nr_trampolines ftrace: Fix trampoline hash update check on rec->flags ring-buffer: Use rb_page_size() instead of open coded head_page size ftrace: Rename ftrace_ops field from trampolines to nr_trampolines tracing: Convert local function_graph functions to static ftrace: Do not copy old hash when resetting tracing: let user specify tracing_thresh after selecting function_graph ring-buffer: Always run per-cpu ring buffer resize with schedule_work_on() tracing: Remove function_trace_stop and HAVE_FUNCTION_TRACE_MCOUNT_TEST s390/ftrace: remove check of obsolete variable function_trace_stop arm64, ftrace: Remove check of obsolete variable function_trace_stop Blackfin: ftrace: Remove check of obsolete variable function_trace_stop metag: ftrace: Remove check of obsolete variable function_trace_stop microblaze: ftrace: Remove check of obsolete variable function_trace_stop MIPS: ftrace: Remove check of obsolete variable function_trace_stop parisc: ftrace: Remove check of obsolete variable function_trace_stop sh: ftrace: Remove check of obsolete variable function_trace_stop sparc64,ftrace: Remove check of obsolete variable function_trace_stop tile: ftrace: Remove check of obsolete variable function_trace_stop ftrace: x86: Remove check of obsolete variable function_trace_stop ...
Diffstat (limited to 'Documentation/trace')
-rw-r--r--Documentation/trace/ftrace-design.txt26
1 files changed, 0 insertions, 26 deletions
diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt
index 3f669b9e885..dd5f916b351 100644
--- a/Documentation/trace/ftrace-design.txt
+++ b/Documentation/trace/ftrace-design.txt
@@ -102,30 +102,6 @@ extern void mcount(void);
EXPORT_SYMBOL(mcount);
-HAVE_FUNCTION_TRACE_MCOUNT_TEST
--------------------------------
-
-This is an optional optimization for the normal case when tracing is turned off
-in the system. If you do not enable this Kconfig option, the common ftrace
-code will take care of doing the checking for you.
-
-To support this feature, you only need to check the function_trace_stop
-variable in the mcount function. If it is non-zero, there is no tracing to be
-done at all, so you can return.
-
-This additional pseudo code would simply be:
-void mcount(void)
-{
- /* save any bare state needed in order to do initial checking */
-
-+ if (function_trace_stop)
-+ return;
-
- extern void (*ftrace_trace_function)(unsigned long, unsigned long);
- if (ftrace_trace_function != ftrace_stub)
-...
-
-
HAVE_FUNCTION_GRAPH_TRACER
--------------------------
@@ -328,8 +304,6 @@ void mcount(void)
void ftrace_caller(void)
{
- /* implement HAVE_FUNCTION_TRACE_MCOUNT_TEST if you desire */
-
/* save all state needed by the ABI (see paragraph above) */
unsigned long frompc = ...;