> -----Original Message-----
> From: Andi Kleen [mailto:a...@firstfloor.org]
> Sent: Wednesday, 24 September, 2014 4:50 PM
> To: Elliott, Robert (Server Storage)
> Cc: Steven Rostedt; linux-kernel@vger.kernel.org; Jens Axboe
> <ax...@kernel.dk> (ax...@kernel.dk); Christoph Hellwig
> Subject: Re: ftrace function-graph and interprocessor interrupts
>
> "Elliott, Robert (Server Storage)" <elli...@hp.com> writes:
>
> > The function-graph tracer marks some interrupt handler functions
> > with ==========> and <========== labels.
>
> I'm not sure the marking is really that useful. Isn't it always obvious
> from the function names where an interrupt starts/end?
>
> -Andi
Although the do_IRQ name stands out pretty well, some of the
others don't, and blk-mq calling them directly makes it hard
to tell. They show up clearly in the function trace, just
not the function_graph trace.
Also, the IPI function can end up nested inside { } but
without indents, depending on when it occurs.
10) |
sd_setup_read_write_cmnd [sd_mod]() {
10) |
smp_call_function_single_interrupt() {
10) | irq_enter() {
...
10) + 36.788 us | } /*
smp_call_function_single_interrupt */
10) | scsi_init_io() {
The ==> labels also add an indent level.
I'd like to add an option to exclude the time taken by interrupts
in the cumulative times, but that first requires that function_graph
understand what times to exclude.
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