Re: perf script doesn't dump a normal call trace

[Xin Long]

On Mon, Nov 5, 2018 at 4:18 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
>
> On Sat, Nov 03, 2018 at 06:36:21PM +0900, Xin Long wrote:
> > On Fri, Nov 2, 2018 at 7:26 PM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
> > >
> > > On Fri, Nov 02, 2018 at 03:36:13PM +0900, Xin Long wrote:
> > > > On upstream kernel(4.19) or RHEL-8 kernel(4.18.0):
> > > >
> > > > # perf record -e 'skb:consume_skb' -ag
> > > > ^C[ perf record: Woken up 1 times to write data ]
> > > > [ perf record: Captured and wrote 0.612 MB perf.data (634 samples) ]
> > > >
> > > > # perf script
> > > > swapper     0 [009] 274370.117711: skb:consume_skb: skbaddr=0xffff962c591d5b00
> > > >         ffffffffa4abe534 consume_skb+0x64 ([kernel.kallsyms])
> > > >
> > > > kworker/9:1-eve   926 [009] 274370.117729: skb:consume_skb:
> > > > skbaddr=0xffff962c591d5b00
> > > >         ffffffffa4abe534 consume_skb+0x64 ([kernel.kallsyms])
> > > >
> > > > kworker/9:1-eve   926 [009] 274370.117732: skb:consume_skb:
> > > > skbaddr=0xffff962c591d4900
> > > >         ffffffffa4abe534 consume_skb+0x64 ([kernel.kallsyms])
> > > >
> > > > swapper     0 [009] 274370.145528: skb:consume_skb: skbaddr=0xffff962c591d4900
> > > >         ffffffffa4abe534 consume_skb+0x64 ([kernel.kallsyms])
> > > >
> > > > kworker/9:1-eve   926 [009] 274370.145545: skb:consume_skb:
> > > > skbaddr=0xffff962c591d4900
> > > >         ffffffffa4abe534 consume_skb+0x64 ([kernel.kallsyms])
> > > >
> > > > kworker/9:1-eve   926 [009] 274370.145547: skb:consume_skb:
> > > > skbaddr=0xffff962c591d5b00
> > > >         ffffffffa4abe534 consume_skb+0x64 ([kernel.kallsyms])
> > > >
> > > > swapper     0 [009] 274370.173443: skb:consume_skb: skbaddr=0xffff962c591d5b00
> > > >         ffffffffa4abe534 consume_skb+0x64 ([kernel.kallsyms])
> > >
> > > I can see that on upstream as well, probably something within
> > > tracepoint entry code, because I have it working nicely when
> > > from kprobe, like:
> > >
> > > [root@ibm-x3650m4-02 perf]# ./perf probe 'consume_skb'
> > > [root@ibm-x3650m4-02 perf]# ./perf record -g -e probe:consume_skb* -aR ^C
> > >
> > Thanks Jiri,
> >
> > My debugging script is using tracepoint with some filters which I
> > don't think probe can support.
> > Any one have fixes for this tracepoint issue?
>
> trying to bisect that.. looks like orc code issue,
> it works for me when you switch to fp unwind:
>   CONFIG_UNWINDER_FRAME_POINTER
>

That's a good workaround, thanks.

Another problem is when I'm using perf built manually from upstream kernel tree,
I couldn't see the function's names.
# perf --version
perf version 4.19.g26f1de

# perf report -T
# To display the perf.data header info, please use
--header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 97  of event 'probe:consume_skb'
# Event count (approx.): 97
#
# Children      Self  Trace output
# ........  ........  ..................
#
   100.00%   100.00%  (ffffffff86f090f0)
            |
            |--93.81%--0xffffffff868000e6
            |          0xffffffff8684ed7f
            |          0xffffffff868e97ad
            |          0xffffffff868e953a
            |          0xffffffff87087623
            |          0xffffffff8682a06f
            |          0xffffffff870872ad
            |          |
            |          |--89.69%--0xffffffff8720098f
            |          |          0xffffffff87201b69
            |          |          0xffffffff868b9c2e


The below is with rhel7's perf
# perf --version
perf version 3.10.0-957.el7.x86_64.debug
# perf report -T
# To display the perf.data header info, please use
--header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 97  of event 'probe:consume_skb'
# Event count (approx.): 97
#
# Children      Self  Trace output
# ........  ........  ..................
#
   100.00%   100.00%  (ffffffff86f090f0)
            |
            |--93.81%--0x2000e6
            |          start_secondary
            |          cpu_startup_entry
            |          do_idle
            |          default_idle_call
            |          arch_cpu_idle
            |          default_idle
            |          |
            |          |--89.69%--ret_from_intr
            |          |          do_IRQ
            |          |          irq_exit