Messages in this thread | | | Date | Mon, 06 Oct 2014 17:35:44 -0400 | From | Steven Rostedt <> | Subject | [PATCH 00/11] [GIT PULL] tracing: Updates for 3.18 |
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Linus,
This set has a few minor updates, but the big change is the redesign of the trampoline logic.
The trampoline logic of 3.17 required a descriptor for every function that is registered to be traced and uses a trampoline. Currently, only the function graph tracer uses a trampoline, but if you were to trace all 32,000 (give or take a few thousand) functions with the function graph tracer, it would create 32,000 descriptors to let us know that there's a trampoline associated with it. This takes up a bit of memory when there's a better way to do it.
The redesign now reuses the ftrace_ops' (what registers the function graph tracer) hash tables. The hash tables tell ftrace what the tracer wants to trace or doesn't want to trace. There's two of them: one that tells us what to trace, the other tells us what not to trace. If the first one is empty, it means all functions should be traced, otherwise only the ones that are listed should be. The second hash table tells us what not to trace, and if it is empty, all functions may be traced, and if there's any listed, then those should not be traced even if they exist in the first hash table.
It took a bit of massaging, but now these hashes can be used to keep track of what has a trampoline and what does not, and allows the ftrace accounting to work. Now we can trace all functions when using the function graph trampoline, and avoid needing to create any special descriptors to hold all the functions that are being traced.
Please pull the latest trace-3.18 tree, which can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git trace-3.18
Tag SHA1: 9e06c8f394155d5501cbd85894562405566d7c43 Head SHA1: 3ddee63a099ebbdc8f84697fe46730b58240c09d
Andreea-Cristina Bernat (1): kernel: trace_syscalls: Replace rcu_assign_pointer() with RCU_INIT_POINTER()
Dave Hansen (1): tracing: generate RCU warnings even when tracepoints are disabled
Steven Rostedt (Red Hat) (9): ftrace: Add separate function for non recursive callbacks ftrace: Add helper function ftrace_ops_get_func() ftrace: Set callback to ftrace_stub when no ops are registered ftrace: Remove freeing of old_hash from ftrace_hash_move() ftrace: Grab any ops for a rec for enabled_functions output ftrace: Annotate the ops operation on update ftrace: Replace tramp_hash with old_*_hash to save space ftrace: Add sanity check when unregistering last ftrace_ops ftrace: Only disable ftrace_enabled to test buffer in selftest
---- include/linux/ftrace.h | 10 +- include/linux/tracepoint.h | 11 ++ kernel/trace/ftrace.c | 416 ++++++++++++++++++++++++------------------ kernel/trace/trace_selftest.c | 4 + kernel/trace/trace_syscalls.c | 4 +- 5 files changed, 267 insertions(+), 178 deletions(-)
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