Function Profiler broken on today's linux-next

[Felipe Balbi]

On Wed, Jul 16, 2014 at 02:54:42PM -0400, Steven Rostedt wrote:
> On Wed, 16 Jul 2014 13:41:52 -0500
> Felipe Balbi <balbi at ti.com> wrote:
> 
> > Hi,
> > 
> > On Wed, Jul 16, 2014 at 01:29:44PM -0500, Felipe Balbi wrote:
> > > On Wed, Jul 16, 2014 at 01:24:13PM -0400, Steven Rostedt wrote:
> > > > On Wed, 16 Jul 2014 11:41:42 -0500
> > > > Felipe Balbi <balbi at ti.com> wrote:
> > > > 
> > > > 
> > > > > .config attached. It's actually an ARM platform, I can help out with
> > > > > testing anything you need.
> > > > 
> > > > In that case, can you see if it works under my repo?
> > > > 
> > > > git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
> > > > branch: ftrace/core
> > > 
> > > works fine, thanks. FWIW
> > > 
> > > Tested-by: Felipe Balbi <balbi at ti.com>
> > 
> > Actually it seems like it's not counting time properly if I run my test
> > multiple times in a row:
> > 
> > # /root/testusb -t 1 -c 100000 -s 2048 -a
> > # head -3 trace_stat/function0
> >   Function                         Hit    Time                Avg           s^2
> >   --------                         ---    ----                ---           ---
> >   thread_interrupt               174876    166120839 us     949.935 us  3048498 us
> > 
> > # /root/testusb -t 1 -c 100000 -s 2048 -a
> > # head -3 trace_stat/function0
> >   Function                           Hit       Time                    Avg          s^2
> >   --------                           ---       ----                    ---          ---
> >   dwc3_thread_interrupt            286796    967267300 us         4190545199 us     3241109 us 
> > 
> > # /root/testusb -t 1 -c 100000 -s 2048 -a
> > # head -3 trace_stat/function0
> >   Function                              Hit      Time                 Avg               s^2
> >     --------                            ---       ----                 ---              ---
> >   dwc3_thread_interrupt               401346    642632072 us       1601.192 us     1194316 us 
> > 
> > and so on...
> > 
> 
> Did it use to work? In other words, is this a regression, or just some
> another bug?

It used to work at least on v3.12... It seems like it's not always
either. After I rebooted, then it took a little effort to trigger it
again. But if I just run my test in a loop, eventually it'll start
miscalculating.

-- 
balbi
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