Re: using SDT events

From: Arnaldo Carvalho de Melo
Date: Wed Sep 28 2016 - 09:35:19 EST


Em Tue, Sep 27, 2016 at 11:40:26AM -0700, Masami Hiramatsu escreveu:
> On Tue, 27 Sep 2016 10:55:38 -0300
> Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote:
>
> > Masami,
> >
> > Testing something else (event aliases/JSON) I saw the many sdt
> > events available via 'perf list', decided to use the usual workflow,
> > failed, what am I doing wrong?
>
> No, that is not supported yet. So I dropped perf-list support from
> the latest series...

Ok, I guess I recall that discussion, will add some warning about that
in the 'perf list' output.

- Arnaldo

> https://lkml.org/lkml/2016/7/1/133
>
> The unresolved problems are
> - how we treat sdt events after recorded? remove or leave it as tracepoint?
> - what should be done if we found the tracepoint which has same name of the
> SDT. (we can not reserve tracepoint name beforehand)
> - Sometimes SDT name can be conflict, even on same binary.
>
>
> >
> >
> > [root@jouet ~]# perf list sdt_qemu:pci*
> >
> > List of pre-defined events (to be used in -e):
> >
> > sdt_qemu:pci_cfg_read [SDT event]
> > sdt_qemu:pci_cfg_write [SDT event]
> > sdt_qemu:pci_update_mappings_add [SDT event]
> > sdt_qemu:pci_update_mappings_del [SDT event]
> > [root@jouet ~]# perf record -e sdt_qemu:pci* -a
> > event syntax error: 'sdt_qemu:pci*'
> > \___ unknown tracepoint
> >
> > Error: File /sys/kernel/debug/tracing/events/sdt_qemu/pci* not found.
> > Hint: Perhaps this kernel misses some CONFIG_ setting to enable this
> > feature?.
> >
> > Run 'perf list' for a list of valid events
> >
> > Usage: perf record [<options>] [<command>]
> > or: perf record [<options>] -- <command> [<options>]
> >
> > -e, --event <event> event selector. use 'perf list' to list
> > available events
> > [root@jouet ~]#
>
>
> --
> Masami Hiramatsu <mhiramat@xxxxxxxxxx>