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Date: Tue, 21 Jun 2016 14:12:38 +0800 From: "Wangnan (F)" <wangnan0@...wei.com> To: Alexei Starovoitov <alexei.starovoitov@...il.com>, "Arnaldo Carvalho de Melo" <acme@...hat.com> CC: Arnaldo Carvalho de Melo <acme@...nel.org>, <linux-kernel@...r.kernel.org>, <pi3orama@....com>, David Ahern <dsahern@...il.com>, Namhyung Kim <namhyung@...il.com>, Alexei Starovoitov <ast@...nel.org>, Jiri Olsa <jolsa@...nel.org> Subject: Re: [PATCH 2/2] perf record: Add --dry-run option to check cmdline options On 2016/6/21 0:22, Alexei Starovoitov wrote: > On Mon, Jun 20, 2016 at 11:38:18AM -0300, Arnaldo Carvalho de Melo wrote: >> Em Mon, Jun 20, 2016 at 11:29:13AM +0800, Wangnan (F) escreveu: >>> On 2016/6/17 0:48, Arnaldo Carvalho de Melo wrote: >>>> Em Thu, Jun 16, 2016 at 08:02:41AM +0000, Wang Nan escreveu: >>>>> With '--dry-run', 'perf record' doesn't do reall recording. Combine with >>>>> llvm.dump-obj option, --dry-run can be used to help compile BPF objects for >>>>> embedded platform. >>>> So these are nice and have value, but can we have a subcommand to do all >>>> this with an expressive name, Something like: >>>> perf bpfcc foo.c -o foo >>>> or shorter: >>>> perf bcc foo.c -o foo >>>> Just like one would use gcc or some other compiler to generate something >>>> for later use? >>> I'll try it today. I thought a subcommand require a bigger feature, >>> and wrapping clang is not big enough. >> Not really, we may have as many as we like, given that they provide >> something useful, like I think is the case here. >> >> Having to edit ~/.perfconfig, create a new section, a variable in it >> with a boolean value (at first, just reading the changeset comment, I >> thought I had to provide a directory where to store the objects >> "dumped"), to then use a tool to record a .c event, but not recording >> (use dry-run, which is useful to test the command line, etc), to then >> get, on the current directory, the end result looked to me a convoluted >> way to ask perf to compile the given .c file into a .o for later use. >> >> Doing: >> >> perf bcc -c foo.c >> >> Looks so much simpler and similar to an existing compile source code >> into object file workflow (gcc's, any C compiler) that I think it would >> fit in the workflow being discussed really nicely. > I'm hopeful that eventually we'll be able merge iovisor/bcc project > with perf, so would be good to reserve 'perf bcc' command for that > future use. Also picking a different name for compiling would be less > confusing to users who already familiar with bcc. Instead we can use: > perf bpfcc foo.c -o foo.o > perf cc foo.c > perf compile foo.c > I think finally we should make perf independent with LLVM runtime. I suggest 'perf bpf' subcommand to deal with all BPF related things, include compiling, configuration and potential cache. Thank you.
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