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

From: Jiri Olsa <[email-masked]>
Date: Wed, 27 Feb 2019 14:21:05 +0100

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:

struct perf_evlist {
	...
	struct {
		pthread_t	th;
		int		state;
	} thread;
};

typedef int (perf_evlist__thread_cb_t)(perf_evlist, union perf_event *event,....)

perf_evlist__start_thread(perf_evlist, perf_evlist__thread_cb_t cb);
perf_evlist__stop_thread(perf_evlist);

jirka