Messages in this thread | | | From | Alexei Starovoitov <> | Subject | Re: [PATCH perf,bpf 5/5] perf util: generate bpf_prog_info_event for short living bpf programs | Date | Wed, 21 Nov 2018 22:49:37 +0000 |
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On 11/21/18 2:35 PM, Song Liu wrote: > > >> On Nov 21, 2018, at 2:11 PM, Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote: >> >> On Wed, Nov 21, 2018 at 11:55:02AM -0800, Song Liu wrote: >>> This patch enables perf-record to listen to bpf_event and generate >>> bpf_prog_info_event for bpf programs loaded and unloaded during >>> perf-record run. >>> >>> To minimize latency between bpf_event and following bpf calls, separate >>> mmap with watermark of 1 is created to process these vip events. Then >>> a separate dummy event is attached to the special mmap. A separate thread >>> is used to only poll bpf events. >>> >>> By default, perf-record will listen to bpf_event. Option no-bpf-event is >>> added in case the user would opt out. >> >> I think only default perf-record for sampling should include it. >> perf record -e for tracepoints, kprobes and anything else should imply no-bpf-event. >> > > Maybe something like > > if (software_event && ! -g) > no_bpf_event = true; > > ? > > This will allow attaching kprobe on bpf helper and see which bpf program > calls it.
right. good point about -g (I assume you mean callgraph collection). Indeed, if bpf progs unload before perf-report they won't be seen in callgraphs too even for sw events, so we have to enable bpf_events to see them.
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