Messages in this thread | | | Date | Thu, 2 Mar 2017 20:09:50 -0500 | From | Steven Rostedt <> | Subject | Re: [PATCH] ftrace: add ftrace_graph_max_depth kernel parameter |
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On Thu, 02 Mar 2017 16:54:57 -0800 Todd Brandt <todd.e.brandt@linux.intel.com> wrote:
> BTW I had one other question for you, is it possible to move the ftrace > module's initialization further up the queue? ATM it initializes at > about 600ms into boot, which is fine since most of the performance > issues are happening at 1000ms+. But eventually it might be nice to > trace some of the earlier init code.
module initialization? Or you mean boot up initialization?
For boot up, we have this:
mm_init(); sched_init(); idr_init_cache(); workqueue_init_early(); rcu_init(); trace_init();
Now, going before mm_init() will definitely be quite a pain, as we that would require making the ring buffer out of early boot memory.
We could add a early_trace_init() just before sched_init(), with some limited tracing. Tracepoints require rcu, although we could make hooks to just do hard coded changes (no rcu synchronization) with a flag that denotes that trace_init() hasn't been called yet.
I could toy with the idea, implement it, and see what breaks.
-- Steve
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