netdev - Re: [PATCH v4 bpf-next 0/4] bpftool: introduce prog profile

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Message-ID: <8855C490-F3E3-4FEB-B59E-C529667BDC30@fb.com>
Date:   Thu, 5 Mar 2020 20:03:53 +0000
From:   Song Liu <songliubraving@...com>
To:     Jiri Olsa <jolsa@...hat.com>
CC:     Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        "quentin@...valent.com" <quentin@...valent.com>,
        Kernel Team <Kernel-team@...com>,
        "ast@...nel.org" <ast@...nel.org>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        "arnaldo.melo@...il.com" <arnaldo.melo@...il.com>,
        "jolsa@...nel.org" <jolsa@...nel.org>
Subject: Re: [PATCH v4 bpf-next 0/4] bpftool: introduce prog profile



> On Mar 4, 2020, at 1:39 PM, Song Liu <songliubraving@...com> wrote:
> 
> 
> 
>> On Mar 4, 2020, at 1:29 PM, Jiri Olsa <jolsa@...hat.com> wrote:
>> 
>> On Wed, Mar 04, 2020 at 09:16:29PM +0000, Song Liu wrote:
>>> 
>>> 
>>>> On Mar 4, 2020, at 12:41 PM, Jiri Olsa <jolsa@...hat.com> wrote:
>>>> 
>>>> On Wed, Mar 04, 2020 at 08:08:07PM +0100, Jiri Olsa wrote:
>>>>> On Wed, Mar 04, 2020 at 10:07:06AM -0800, Song Liu wrote:
>>>>>> This set introduces bpftool prog profile command, which uses hardware
>>>>>> counters to profile BPF programs.
>>>>>> 
>>>>>> This command attaches fentry/fexit programs to a target program. These two
>>>>>> programs read hardware counters before and after the target program and
>>>>>> calculate the difference.
>>>>>> 
>>>>>> Changes v3 => v4:
>>>>>> 1. Simplify err handling in profile_open_perf_events() (Quentin);
>>>>>> 2. Remove redundant p_err() (Quentin);
>>>>>> 3. Replace tab with space in bash-completion; (Quentin);
>>>>>> 4. Fix typo _bpftool_get_map_names => _bpftool_get_prog_names (Quentin).
>>>>> 
>>>>> hum, I'm getting:
>>>>> 
>>>>> 	[jolsa@...l-r440-01 bpftool]$ pwd
>>>>> 	/home/jolsa/linux-perf/tools/bpf/bpftool
>>>>> 	[jolsa@...l-r440-01 bpftool]$ make
>>>>> 	...
>>>>> 	make[1]: Leaving directory '/home/jolsa/linux-perf/tools/lib/bpf'
>>>>> 	  LINK     _bpftool
>>>>> 	make: *** No rule to make target 'skeleton/profiler.bpf.c', needed by 'skeleton/profiler.bpf.o'. Stop.
>>>> 
>>>> ok, I had to apply your patches by hand, because 'git am' refused to
>>>> due to fuzz.. so some of you new files did not make it to my tree ;-)
>>>> 
>>>> anyway I hit another error now:
>>>> 
>>>> 	  CC       prog.o
>>>> 	In file included from prog.c:1553:
>>>> 	profiler.skel.h: In function ‘profiler_bpf__create_skeleton’:
>>>> 	profiler.skel.h:136:35: error: ‘struct profiler_bpf’ has no member named ‘rodata’
>>>> 	  136 |  s->maps[4].mmaped = (void **)&obj->rodata;
>>>> 	      |                                   ^~
>>>> 	prog.c: In function ‘profile_read_values’:
>>>> 	prog.c:1650:29: error: ‘struct profiler_bpf’ has no member named ‘rodata’
>>>> 	 1650 |  __u32 m, cpu, num_cpu = obj->rodata->num_cpu;
>>>> 
>>>> I'll try to figure it out.. might be error on my end
>>>> 
>>>> do you have git repo with these changes?
>>> 
>>> I pushed it to 
>>> 
>>> https://git.kernel.org/pub/scm/linux/kernel/git/song/linux.git/tree/?h=bpf-per-prog-stats
>> 
>> still the same:
>> 
>> 	[jolsa@...l-r440-01 bpftool]$ git show --oneline HEAD | head -1
>> 	7bbda5cca00a bpftool: fix typo in bash-completion
>> 	[jolsa@...l-r440-01 bpftool]$ make 
>> 	make[1]: Entering directory '/home/jolsa/linux-perf/tools/lib/bpf'
>> 	make[1]: Leaving directory '/home/jolsa/linux-perf/tools/lib/bpf'
>> 	  CC       prog.o
>> 	In file included from prog.c:1553:
>> 	profiler.skel.h: In function ‘profiler_bpf__create_skeleton’:
>> 	profiler.skel.h:136:35: error: ‘struct profiler_bpf’ has no member named ‘rodata’
>> 	  136 |  s->maps[4].mmaped = (void **)&obj->rodata;
>> 	      |                                   ^~
>> 	prog.c: In function ‘profile_read_values’:
>> 	prog.c:1650:29: error: ‘struct profiler_bpf’ has no member named ‘rodata’
>> 	 1650 |  __u32 m, cpu, num_cpu = obj->rodata->num_cpu;
>> 	      |                             ^~
>> 	prog.c: In function ‘profile_open_perf_events’:
>> 	prog.c:1810:19: error: ‘struct profiler_bpf’ has no member named ‘rodata’
>> 	 1810 |   sizeof(int), obj->rodata->num_cpu * obj->rodata->num_metric);
>> 	      |                   ^~
>> 	prog.c:1810:42: error: ‘struct profiler_bpf’ has no member named ‘rodata’
>> 	 1810 |   sizeof(int), obj->rodata->num_cpu * obj->rodata->num_metric);
>> 	      |                                          ^~
>> 	prog.c:1825:26: error: ‘struct profiler_bpf’ has no member named ‘rodata’
>> 	 1825 |   for (cpu = 0; cpu < obj->rodata->num_cpu; cpu++) {
>> 	      |                          ^~
>> 	prog.c: In function ‘do_profile’:
>> 	prog.c:1904:13: error: ‘struct profiler_bpf’ has no member named ‘rodata’
>> 	 1904 |  profile_obj->rodata->num_cpu = num_cpu;
>> 	      |             ^~
>> 	prog.c:1905:13: error: ‘struct profiler_bpf’ has no member named ‘rodata’
>> 	 1905 |  profile_obj->rodata->num_metric = num_metric;
>> 	      |             ^~
>> 	make: *** [Makefile:129: prog.o] Error 1
> 
> I guess you need a newer version of clang that supports global data in BPF programs. 

Hi Jiri,

Have you got chance to test this with latest clang? 

Thanks,
Song