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Date: Fri, 7 Aug 2015 10:43:38 -0300 From: Arnaldo Carvalho de Melo <acme@...hat.com> To: "Wangnan (F)" <wangnan0@...wei.com> Cc: ast@...mgrid.com, daniel@...earbox.net, David Ahern <dsahern@...il.com>, hekuang@...wei.com, Jiri Olsa <jolsa@...nel.org>, xiakaixu@...wei.com, masami.hiramatsu.pt@...achi.com, Namhyung Kim <namhyung@...il.com>, a.p.zijlstra@...llo.nl, lizefan@...wei.com, pi3orama@....com, acme@...nel.org, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...nel.org> Subject: Re: [PATCH 09/20] perf tools: Parse probe points of eBPF programs during preparation Adding back lkml and Ingo, noticed it wasn't there :-\ Em Fri, Aug 07, 2015 at 01:27:39PM +0800, Wangnan (F) escreveu: > On 2015/8/6 23:50, Arnaldo Carvalho de Melo wrote: > >Em Tue, Aug 04, 2015 at 06:28:38AM +0000, Wang Nan escreveu: > >>This patch parses section name of each program, and creates > >>corresponding 'struct perf_probe_event' structure. > >> > >>parse_perf_probe_command() is used to do the main parsing works. > >>Parsing result is stored into a global array. This is because > >>add_perf_probe_events() is non-reentrantable. In following patch, > >>add_perf_probe_events will be introduced to insert kprobes. It accepts > >>an array of 'struct perf_probe_event' and do all works in one call. > >> > >>Define PERF_BPF_PROBE_GROUP as "perf_bpf_probe", which will be used > >>as group name of all eBPF probing points. > >> > >>This patch utilizes bpf_program__set_private(), bind perf_probe_event > >>with bpf program by private field. > >This patch reports errors via pr_err(), which is suboptimal because it > >assumes that the interface to these facilities use a stdout UI. > > Can I fix it using one patch after all staffs in > tools/perf/utils/bpf-loader.c > goes into your tree? Sure > >I guess we can have it as is now, because the initial use cases is stdio > >based, but we need to move this to use bpf__strerror() routines like we > >do elsewhere in tools/perf/, i.e. see: > > > >int perf_evlist__strerror_open(struct perf_evlist *evlist __maybe_unused, > > int err, char *buf, size_t size) > > > >int perf_evlist__strerror_mmap(struct perf_evlist *evlist, int err, > > char *buf, size_t size) > > > >I.e. we have multiple CLASS__strerror_API to map errors we return (that > >int err) to strings that we store in buf, following the strerror_r() > >model. > > > >I.e. these libraries should not emit errors, at most they can emit log > >messages (pr_debug), but direct user interaction should be done via UI > >code (tools/perf/ui/) and tools/perf/builtin-foo.c files. > > > >Also the global thing suckz rockz, again, may be acceptable at this > >point due to friction with how the existing probing routines are > >structured, but we need to make those functions better, not work around > >what seems to be limitations they have. > > Also for this one, since it is a fundamental problem in probe related > code. However, I think global thing can be avoided by moving this patch > after 'perf probe: Attach trace_probe_event with perf_probe_event', > config programs at the head of bpf__probe(). Right, I'm preparing a pull req for up to the 'perf test LLVM' patch, which I think we went thru enough iterations, that way we erode this patchkit a bit more, as 4 patches are already in tip.git, from yesterday's pull req I sent to Ingo, yay! > Thank you. Thanks! - Arnaldo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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