linux-kernel - Re: [PATCH] perf test: Add bpf-output event

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Message-ID: <564E83E2.6010503@huawei.com>
Date:	Fri, 20 Nov 2015 10:22:26 +0800
From:	"Wangnan (F)" <wangnan0@...wei.com>
To:	Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
CC:	Alexei Starovoitov <alexei.starovoitov@...il.com>,
	"Arnaldo Carvalho de Melo" <acme@...nel.org>,
	Jiri Olsa <jolsa@...hat.com>, <ast@...nel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] perf test: Add bpf-output event



On 2015/11/20 7:29, Sukadev Bhattiprolu wrote:
> Wangnan (F) [wangnan0@...wei.com] wrote:
> |
> |
> | On 2015/11/19 7:14, Alexei Starovoitov wrote:
> | >On Wed, Nov 18, 2015 at 05:50:39PM -0300, Arnaldo Carvalho de Melo wrote:
> | >>Em Wed, Nov 18, 2015 at 11:26:04AM -0800, Sukadev Bhattiprolu escreveu:
> | >>>>From 8f71d55dd3e27e6ca2138e3ed6dfeceb1c00a426 Mon Sep 17 00:00:00 2001
> | >>>From: Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
> | >>>Date: Wed, 18 Nov 2015 19:06:08 -0500
> | >>>Subject: [PATCH] perf test: Add bpf-output event
> | >>>
> | >>>The kernel has added support for 'PERF_COUNT_SW_BPF_OUTPUT' but that is
> | >>>missing from the perf tool. Among other things, results in the 'roundtrip
> | >>>evsel->name check' test case of 'perf test' failing on Powerpc.
> | >>Next time can you please state if this is for this merge window or for
> | >>the next?
> | >>
> | >>Will apply it for perf/core, for the next merge window.
> | >wait a sec, I believe Wang has posted an RFC a month ago that adds support
> | >for this properly instead of simply shutting up the error.
> |
> | Yes. Please have a look at
> |
> | http://lkml.kernel.org/g/1446029705-199659-3-git-send-email-wangnan0@huawei.com
> |
> | and patch 23/31 - 31/31 in
> |
> | http://lkml.kernel.org/g/1444826502-49291-1-git-send-email-wangnan0@huawei.com
> |
> | We are working on a solution which truly utilizes bpf-output, including
> | filling event array and extracting BPF output through perf data to CTF
> | format. Now they are separated in multiple patchset, and I'd like to
> | resend them to Arnaldo in this week.
>
> Ok. It looked like there was development going on around BPF so I put
> in the stubs to avoid false positives in the perf test.  There is a BPF
> filter test case that is also getting Skipped. Would this patchset address
> that too?

Do you mean this?

$ ./perf test bpf
37: Test BPF filter                                          :
37.1: Test basic BPF filtering                               : Skip

To make it pass you need to build BPF compiling environment first.

First of all you must be root:

$ ./perf test -v bpf
37: Test BPF filter                                          :
37.1: Test basic BPF filtering                               :
--- start ---
test child forked, pid 19359
Only root can run BPF test
test child finished with -2
---- end ----
Test BPF filter subtest 0: Skip


Then it would tell you how to setup your LLVM environment:

$ sudo -s
# ./perf test -v bpf
37: Test BPF filter                                          :
37.1: Test basic BPF filtering                               :
--- start ---
test child forked, pid 19463
ERROR:    unable to find clang.
Hint:    Try to install latest clang/llvm to support BPF. Check your $PATH
          and 'clang-path' option in [llvm] section of ~/.perfconfig.
          LLVM 3.7 or newer is required. Which can be found from 
http://llvm.org
          You may want to try git trunk:
              git clone http://llvm.org/git/llvm.git
                   and
              git clone http://llvm.org/git/clang.git

          Or fetch the latest clang/llvm 3.7 from pre-built llvm 
packages for
          debian/ubuntu:
              http://llvm.org/apt

          If you are using old version of clang, change 
'clang-bpf-cmd-template'
          option in [llvm] section of ~/.perfconfig to:

            "$CLANG_EXEC $CLANG_OPTIONS $KERNEL_INC_OPTIONS \
               -working-directory $WORKING_DIR -c $CLANG_SOURCE \
               -emit-llvm -o - | /path/to/llc -march=bpf -filetype=obj -o -"
          (Replace /path/to/llc with path to your llc)

Failed to compile test case: 'Basic BPF llvm compiling test'
Unable to get BPF object, fix 'perf test LLVM' first
test child finished with -2
---- end ----
Test BPF filter subtest 0: Skip


Set your clang path to ~/.perfconfig

# cat ~/.perfconfig
[llvm]
     clang-path = "/opt/llvm-3.7.0/x86_64-oe-linux-clang"

Then try 'perf test LLVM', fix all failure:

# ./perf test LLVM
35: Test LLVM searching and compiling                        :
35.1: Basic BPF llvm compiling test                          : Ok
35.2: Test kbuild searching                                  : Ok
35.3: Compile source for BPF prologue generation test        : Ok

After that you can try perf test BPF:

# ./perf test BPF
37: Test BPF filter                                          :
37.1: Test basic BPF filtering                               : Ok
37.2: Test BPF prologue generation                           : Ok

Thank you.


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