From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752151AbbCWJ2K (ORCPT ); Mon, 23 Mar 2015 05:28:10 -0400 Received: from [133.145.228.44] ([133.145.228.44]:57165 "EHLO mail9.hitachi.co.jp" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751935AbbCWJ2H (ORCPT ); Mon, 23 Mar 2015 05:28:07 -0400 Message-ID: <550FDC8A.5010100@hitachi.com> Date: Mon, 23 Mar 2015 18:27:38 +0900 From: Masami Hiramatsu Organization: Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: Alexei Starovoitov CC: Ingo Molnar , Steven Rostedt , Namhyung Kim , Arnaldo Carvalho de Melo , Jiri Olsa , "David S. Miller" , Daniel Borkmann , Peter Zijlstra , linux-api@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: bpf+tracing next steps. Was: [PATCH v9 tip 3/9] tracing: attach BPF programs to kprobes References: <1426894210-27441-1-git-send-email-ast@plumgrid.com> <1426894210-27441-4-git-send-email-ast@plumgrid.com> <550D60C2.8010502@hitachi.com> <550D962E.7010400@plumgrid.com> <550E9421.7030507@hitachi.com> <550F0402.80900@plumgrid.com> <550F77B3.1020802@hitachi.com> <550F9D20.7070006@plumgrid.com> In-Reply-To: <550F9D20.7070006@plumgrid.com> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2015/03/23 13:57), Alexei Starovoitov wrote: > On 3/22/15 7:17 PM, Masami Hiramatsu wrote: >> (2015/03/23 3:03), Alexei Starovoitov wrote: >> >>> User space tools that will compile ktap/dtrace scripts into bpf might >>> use build-id for their own purpose, but that's a different discussion. >> >> Agreed. >> I'd like to discuss it since kprobe event interface may also have same >> issue. > > I'm not sure what 'issue' you're seeing. My understanding is that > build-ids are used by perf to associate binaries with their debug info > and by systemtap to make sure that probes actually match the kernel > they were compiled for. In bpf case it probably will be perf way only. Ah, I see. So perftools can check the build-id if needed, right? > Are you interested in doing something with bpf ? ;) Of course :) > I know that Jovi is working on clang-based front-end, He Kuang is doing > something fancy and I'm going to focus on 'tcp instrumentation' once > bpf+kprobes is in. I think these efforts will help us make it > concrete and will establish a path towards bpf+tracepoints > (debug tracepoints or trace markers) and eventual integration with perf. > Here is the wish-list (for kernel and userspace) inspired by Brendan: > - access to pid, uid, tid, comm, etc > - access to kernel stack trace > - access to user-level stack trace > - kernel debuginfo for walking kernel structs, and accessing kprobe > entry args as variables perf probe can provide this to bpf. > - tracing of uprobes > - tracing of user markers I'm working on the perf-cache which will also support SDT (based on Hemant Kumar's work). > - user debuginfo for user structs and args Ditto. > - easy to use language > - library of scripting features > - nice one-liner syntax > > I think there is a lot of interest in bpf+tracing and would be good to > align the efforts. Agreed :) Thanks! -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com