Messages in this thread | | | From | Song Liu <> | Subject | Re: [RFC perf,bpf 5/5] perf util: generate bpf_prog_info_event for short living bpf programs | Date | Tue, 6 Nov 2018 23:17:51 +0000 |
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> On Nov 6, 2018, at 1:54 PM, David Ahern <dsahern@gmail.com> wrote: > > On 11/6/18 1:52 PM, Song Liu wrote: >> + >> static int record__mmap_read_all(struct record *rec) >> { >> int err; >> >> + err = record__mmap_process_vip_events(rec); >> + if (err) >> + return err; >> + >> err = record__mmap_read_evlist(rec, rec->evlist, false); >> if (err) >> return err; > > Seems to me that is going to increase the overhead of perf on any system > doing BPF updates. The BPF events cause a wakeup every load and unload, > and perf processes not only the VIP events but then walks all of the > other maps.
BPF prog load/unload events should be rare events in real world use cases. So I think the overhead is OK. Also, I don't see an easy way to improve this.
> >> @@ -1686,6 +1734,8 @@ static struct option __record_options[] = { >> "signal"), >> OPT_BOOLEAN(0, "dry-run", &dry_run, >> "Parse options then exit"), >> + OPT_BOOLEAN(0, "no-bpf-event", &record.no_bpf_event, >> + "do not record event on bpf program load/unload"), > > Why should this default on? If am recording FIB events, I don't care > about BPF events. >
I am OK with default off if that's the preferred way.
Thanks, Song
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