Re: [RFC PATCH 0/2] libtraceevent/perf: Add support for trace-cmd plugins

[Steven Rostedt <rostedt@goodmis.org>]

On Tue, 2012-06-19 at 10:11 +0900, Namhyung Kim wrote:

> > trace-cmd report -N
> > [...]
> >              kvm-6172  [000] 14669573.114126: kvm_entry:            vcpu 0
> >              kvm-6172  [000] 14669573.114127: kvm_exit:             [FAILED TO PARSE] exit_reason=30 guest_rip=0xffff357a isa=1 info1=217841672 info2=0
> >              kvm-6172  [000] 14669573.114130: kvm_emulate_insn:     [FAILED TO PARSE] rip=4294915450 csbase=0 len=1 insn=ì[ÃWVS<89>Ã<89>Öš^Gu^Q^O^E flags=5 failed=0
> >              kvm-6172  [000] 14669573.114130: kvm_pio:              pio_read at 0xcfc size 1 count 1
> >              kvm-6172  [000] 14669573.114131: kvm_userspace_exit:   reason KVM_EXIT_IO (2)
> >              kvm-6172  [000] 14669573.114134: kvm_entry:            vcpu 0
> >
> 
> What I want to do is make it not to fail with default print_fmt (ie. w/o
> plugin support). IOW using a plugin to improve things like above is
> good, but not using it shouldn't break/fail anything. So I think fixing
> the TP_printk is needed.

I'm not sure its broken anymore per-say. As I just ran this without
plugins (with the -N switch) and it doesn't break. It sends out some
nasty warnings, but continues on its happy way with a warning that it
'[FAILED TO PARSE]'. And some warnings in the beginning.

But it doesn't totally fail. We could probably clean it up a bit too.
What it does above is simply print out the raw data and lists the
fields.

The problem with modifying the TP_printk() is that this is also used by
raw tracing (the /debug/tracing/trace file). Without using tools. The
TP_printk() is really for that. The plugins is the way for tools to
handle it.

-- Steve