Re: [PATCH v4 perf,bpf 14/15] perf: introduce side band thread

From: Jiri Olsa
Date: Mon Mar 04 2019 - 15:41:06 EST


On Mon, Mar 04, 2019 at 07:49:06PM +0000, Song Liu wrote:
>
>
> > On Mar 4, 2019, at 5:52 AM, Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
> >
> > On Wed, Feb 27, 2019 at 05:52:52PM +0000, Song Liu wrote:
> >>
> >>
> >>> On Feb 27, 2019, at 5:21 AM, Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
> >>>
> >>> On Mon, Feb 25, 2019 at 04:20:18PM -0800, Song Liu wrote:
> >>>
> >>> SNIP
> >>>
> >>>> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> >>>> index 8c902276d4b4..61b87c8111e6 100644
> >>>> --- a/tools/perf/util/evlist.c
> >>>> +++ b/tools/perf/util/evlist.c
> >>>> @@ -19,6 +19,7 @@
> >>>> #include "debug.h"
> >>>> #include "units.h"
> >>>> #include "asm/bug.h"
> >>>> +#include "bpf-event.h"
> >>>> #include <signal.h>
> >>>> #include <unistd.h>
> >>>>
> >>>> @@ -1841,3 +1842,102 @@ struct perf_evsel *perf_evlist__reset_weak_group(struct perf_evlist *evsel_list,
> >>>> }
> >>>> return leader;
> >>>> }
> >>>> +
> >>>> +static struct perf_evlist *sb_evlist;
> >>>> +pthread_t poll_thread;
> >>>
> >>> so some of the things are static and some like poll_args
> >>> you alloced on the stack.. I dont like this interface,
> >>> could we come up with something generic? perhaps
> >>> encapsulated in perf_evlist, like:
> >>
> >> I picked global sb_evlist and poll_thread because there
> >> should be only one sb_evlist and one thread polling it.
> >> There might be multiple evsel on the sb_evlist.
> >>
> >> I am not sure I understand your suggestion..
> >>
> >>> struct perf_evlist {
> >>> ...
> >>> struct {
> >>> pthread_t th;
> >>> int state;
> >>> } thread;
> >>
> >> This will not be used by the main perf_evlist, right?
> >
> > no, just by the thread interface
>
> What is "state" here?

it's replacement for the 'done' pointer u had,
which I did not like.. leting each thread having
its own state is better IMO

jirka