Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757446Ab3IMCCS (ORCPT ); Thu, 12 Sep 2013 22:02:18 -0400 Received: from mail4.hitachi.co.jp ([133.145.228.5]:38979 "EHLO mail4.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755687Ab3IMCCR (ORCPT ); Thu, 12 Sep 2013 22:02:17 -0400 X-AuditID: 85900ec0-d1d29b9000001514-a4-5232722557f9 Subject: [PATCH V2 0/5] trace-cmd: Support the feature recording trace data of guests on the host To: Steven Rostedt From: Yoshihiro YUNOMAE Cc: Hidehiro Kawai , Masami Hiramatsu , linux-kernel@vger.kernel.org, yrl.pp-manager.tt@hitachi.com Date: Fri, 13 Sep 2013 11:06:27 +0900 Message-ID: <20130913020627.28927.69090.stgit@yunodevel> User-Agent: StGit/0.16 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8144 Lines: 184 Hi Steven, This is a v2 patch set for realizing a part of "Integrated trace" feature which is a trace merging system for a virtualization environment. Currently, trace-cmd does not have following features yet: a) Server and client for a virtualization environment b) Structured message platform between guests and host c) Agent feature of a client d) Merge feature of trace data of multiple guests and host in chronological order This patch set supports above a) and b) features. +------------+ +------------+ Guest | a), c) | | a), c) | client/agent ^ +------------+ +------------+ | ^ ^ ^ ^ ============|===|=================|===|=========== | v b)v v b)v v +----------------------------------+ Host | a) | server +----------------------------------+ ||output || || \/ \/ \/ /--------+ /--------+ /--------+ | 010101 | | 101010 | | 100101 | binary data | 010100 | | 010100 | | 110011 | +--------+ +--------+ +--------+ \ / \-----------------------------------/ || d) \/ /-----------------------------------+ | (guest1) 123456: sched_switch... | text data | (guest2) 123458: kmem_free... | | (host) 123500: kvm_exit (guest1)| | (host) 123510: kvm_entry(guest1)| | (guest1) 123550: sched_switch... | +-----------------------------------+ a) Server and client for a virtualization environment trace-cmd has listen mode for network, but using network will be a high cost operation for inducing a lot of memory copying. From kernel-3.6, the virtio-console driver supports splice_write and ftrace supports "steal" for fops. So, guest clients of trace-cmd can send trace data without copying memory by using splice(2). If guest clients use virtio-serial, the server also needs to support virtio-serial I/F. b) Structured message platform between guests and a host Currently, a server(clients) sends unstructured character string to clients(server), so clients(server) must parse the unstructured messages. Since it is hard to add complex contents in the protocol, structured binary message trace-msg is introduced as the communication protocol. c) Agent feature of a client Current trace-cmd client can operate only as "record" mode, so the client will send trace data to the server immediately. However, when an user tries to collect trace data of multiple guests on a host, the user must log in to each guest. This is hard to use, I think. So, trace-cmd client had better support agent mode which receives a message from the server. d) Merge feature of trace data of multiple guests and a host in chronological order Current trace-cmd has a merge feature for multiple machines whose times are synchronized by NTP. When we use the feature, we execute "trace-cmd record" with --date option on each machine, and then we run "trace-cmd report" with -i option for each file. However, there are cases that times of those machines cannot be synchronized. For example, although multiple users can run guests on virtualization environments (e.g. multi-tenant cloud hosting), there are no guarantee that they use the same NTP server. Moreover, even if the times are synchronized, trace data cannot exactly be merged because the NTP-synchronized time granularity may not be enough fine for sorting guest-host switching events. So, I'm considering that trace data use x86-tsc as timestamp in order to merge trace data. By using x86-tsc, we can merge trace data even if time of those machines is not synchronized when CPU has the invariant TSC feature or the constant TSC feature. And the precision will be enough for understanding operations of guests and host. However, TSC values on a guest are not equal to the values on the host because TSC_guest = TSC_host + TSC_offset. This series actually doesn't support TSC offset, but I'd like to add such feature to fix host/guest clock difference in the other series. TSC offset values can be gotten as write_tsc_offset trace event from kernel-3.11. (see https://lkml.org/lkml/2013/6/12/72) For a), this patch introduces "virt-server" and "record --virt" modes for achieving low-overhead communication of trace data of guests. "virt-server" is a server mode for collecting trace data of guests. On the other hand, "record --virt" mode is a guest client for sending trace data of the guest. Although these functions are similar to "listen" and "record -N" modes each, these do not use network but use virtio-serial for low-overhead communication. For b), this patch series introduce specific message protocol in order to handle communication messages with 8 commands. When we extend any messages, using structured message will be easier than using unstructured message. 1. Run virt-server on a host # trace-cmd virt-server 2. Make guest domain directory # mkdir -p /tmp/trace-cmd/virt/ # chmod 710 /tmp/trace-cmd/virt/ # chgrp qemu /tmp/trace-cmd/virt/ 3. Make FIFO on the host # mkfifo /tmp/trace-cmd/virt//trace-path-cpu{0,1,...,X}.{in,out} 4. Set up of virtio-serial pipe of a guest on the host Add the following tags to domain XML files. # virsh edit ... (cpu1, cpu2, ...) 5. Boot the guest # virsh start 6. Execute "record --virt" on the guest # trace-cmd record --virt -e sched* I measured CPU usage outputted by top command on a guest when client sends trace data. Client means "record -N"(NW) or "record --virt"(virtio-serial). NW virtio-serial(splice) client(fedora19) ~2.9[%] ~1.7[%] - Add an agent mode based on "record --virt" - Add a merging feature of trace data of guests and host to "report" Changes in V2: [1/5] Add a comment in open_udp() [2/5] Regacy protocol support in order to keep backward compatibility Thank you, --- Yoshihiro YUNOMAE (5): [CLEANUP] trace-cmd: Split out binding a port and fork reader from open_udp() trace-cmd: Apply the trace-msg protocol for communication between a server and clients trace-cmd: Use poll(2) to wait for a message trace-cmd: Add virt-server mode for a virtualization environment trace-cmd: Add --virt option for record mode Documentation/trace-cmd-record.1.txt | 11 Documentation/trace-cmd-virt-server.1.txt | 89 +++ Makefile | 2 trace-cmd.c | 3 trace-cmd.h | 14 trace-listen.c | 601 ++++++++++++++++---- trace-msg.c | 874 +++++++++++++++++++++++++++++ trace-msg.h | 31 + trace-output.c | 4 trace-record.c | 146 ++++- trace-recorder.c | 54 +- trace-usage.c | 10 12 files changed, 1678 insertions(+), 161 deletions(-) create mode 100644 Documentation/trace-cmd-virt-server.1.txt create mode 100644 trace-msg.c create mode 100644 trace-msg.h -- Yoshihiro YUNOMAE Software Platform Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: yoshihiro.yunomae.ez@hitachi.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/