Subject: Re: [PATCH v7 perf,bpf 07/15] perf, bpf: save bpf_prog_info information as headers to perf.data

From: Jiri Olsa <[email-masked]>
Date: Mon, 11 Mar 2019 18:56:54 +0100

On Thu, Mar 07, 2019 at 09:58:02AM -0800, Song Liu wrote:
> This patch enables perf-record to save bpf_prog_info information as
> headers to perf.data. A new header type HEADER_BPF_PROG_INFO is
> introduced for this data.
> 
> Signed-off-by: Song Liu <[email-masked]>
> ---
>  tools/perf/util/header.c | 145 ++++++++++++++++++++++++++++++++++++++-
>  tools/perf/util/header.h |   1 +
>  2 files changed, 145 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> index 4b88de5e9192..f0708188211e 100644
> --- a/tools/perf/util/header.c
> +++ b/tools/perf/util/header.c
> @@ -18,6 +18,7 @@
>  #include <sys/utsname.h>
>  #include <linux/time64.h>
>  #include <dirent.h>
> +#include <bpf/libbpf.h>
>  
>  #include "evlist.h"
>  #include "evsel.h"
> @@ -39,6 +40,7 @@
>  #include "tool.h"
>  #include "time-utils.h"
>  #include "units.h"
> +#include "bpf-event.h"
>  
>  #include "sane_ctype.h"
>  
> @@ -1074,6 +1076,54 @@ static int write_clockid(struct feat_fd *ff,
>  			sizeof(ff->ph->env.clockid_res_ns));
>  }
>  
> +static int write_bpf_prog_info(struct feat_fd *ff,
> +			       struct perf_evlist *evlist __maybe_unused)
> +{
> +	struct perf_env *env = &ff->ph->env;
> +	struct rb_root *root;
> +	struct rb_node *next;
> +	u32 count = 0;
> +	int ret;
> +
> +	down_read(&env->bpf_progs.lock);
> +
> +	root = &env->bpf_progs.infos;
> +	next = rb_first(root);
> +	while (next) {
> +		++count;
> +		next = rb_next(next);
> +	}

sry I did not se this before, but why you don't keep program count
in perf_env::bpf_progs::infos_cnt ?

jirka