From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3B056C43603 for ; Wed, 4 Dec 2019 21:36:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0B19E206DF for ; Wed, 4 Dec 2019 21:36:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728011AbfLDVf7 (ORCPT ); Wed, 4 Dec 2019 16:35:59 -0500 Received: from mail.kernel.org ([198.145.29.99]:33062 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727982AbfLDVf7 (ORCPT ); Wed, 4 Dec 2019 16:35:59 -0500 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 807C5206DF; Wed, 4 Dec 2019 21:35:58 +0000 (UTC) Date: Wed, 4 Dec 2019 16:35:56 -0500 From: Steven Rostedt To: "Tzvetomir Stoyanov (VMware)" Cc: linux-trace-devel@vger.kernel.org Subject: Re: [PATCH v17 07/18] trace-cmd: Find and store pids of tasks, which run virtual CPUs of given VM Message-ID: <20191204163556.197cc4f3@gandalf.local.home> In-Reply-To: <20191203103522.482684-8-tz.stoyanov@gmail.com> References: <20191203103522.482684-1-tz.stoyanov@gmail.com> <20191203103522.482684-8-tz.stoyanov@gmail.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-trace-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org On Tue, 3 Dec 2019 12:35:11 +0200 "Tzvetomir Stoyanov (VMware)" wrote: > From: Tzvetomir Stoyanov > > In order to match host and guest events, a mapping between guest VCPU > and the host task, running this VCPU is needed. Extended existing > struct guest to hold such mapping and added logic in read_qemu_guests() > function to initialize it. Implemented a new internal API, > get_guest_vcpu_pid(), to retrieve VCPU-task mapping for given VM. > > Signed-off-by: Tzvetomir Stoyanov > --- > tracecmd/include/trace-local.h | 2 ++ > tracecmd/trace-record.c | 57 ++++++++++++++++++++++++++++++++++ > 2 files changed, 59 insertions(+) > > diff --git a/tracecmd/include/trace-local.h b/tracecmd/include/trace-local.h > index a51f0d0..51abef1 100644 > --- a/tracecmd/include/trace-local.h > +++ b/tracecmd/include/trace-local.h > @@ -243,6 +243,8 @@ void update_first_instance(struct buffer_instance *instance, int topt); > > void show_instance_file(struct buffer_instance *instance, const char *name); > > +int get_guest_vcpu_pid(unsigned int guest_cid, unsigned int guest_vcpu); > + > /* moved from trace-cmd.h */ > void tracecmd_create_top_instance(char *name); > void tracecmd_remove_instances(void); > diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c > index 4459c90..fd7ca82 100644 > --- a/tracecmd/trace-record.c > +++ b/tracecmd/trace-record.c > @@ -2873,10 +2873,12 @@ static bool is_digits(const char *s) > return true; > } > > +#define VCPUS_MAX 256 > struct guest { > char *name; > int cid; > int pid; > + int cpu_pid[VCPUS_MAX]; > }; > > static struct guest *guests; > @@ -2894,6 +2896,46 @@ static char *get_qemu_guest_name(char *arg) > return arg; > } > > +static void read_qemu_guests_pids(char *guest_task, struct guest *guest) > +{ > + struct dirent *entry; > + char path[PATH_MAX]; > + char *buf = NULL; > + size_t n = 0; > + int vcpu; > + DIR *dir; > + FILE *f; > + > + snprintf(path, sizeof(path), "/proc/%s/task", guest_task); > + dir = opendir(path); > + if (!dir) > + return; > + > + while ((entry = readdir(dir))) { > + if (!(entry->d_type == DT_DIR && is_digits(entry->d_name))) > + continue; > + > + snprintf(path, sizeof(path), "/proc/%s/task/%s/comm", > + guest_task, entry->d_name); > + f = fopen(path, "r"); > + if (!f) > + continue; > + if (getline(&buf, &n, f) < 0) > + goto next; > + if (strncmp(buf, "CPU ", 4) != 0) > + goto next; > + > + vcpu = atoi(buf+4); > + if (!(vcpu >= 0 && vcpu < VCPUS_MAX)) > + goto next; > + guest->cpu_pid[vcpu] = atoi(entry->d_name); > + > +next: I don't usually mind goto's but the above could be simply written as: if (getline(&buf, &n, f) >= 0 && strncmp(buf, "CPU ", 4) == 0) { vcpu = atoi(buf + 4); if (vcpu >= 0 && vcpu < VCPUS_MAX) guest->cpu_pid[vcpu] = atoi(entry->d_name); } -- Steve > + fclose(f); > + } > + free(buf); > +} > + > static void read_qemu_guests(void) > { > static bool initialized; > @@ -2957,6 +2999,8 @@ static void read_qemu_guests(void) > if (!is_qemu) > goto next; > > + read_qemu_guests_pids(entry->d_name, &guest); > + > guests = realloc(guests, (guests_len + 1) * sizeof(*guests)); > if (!guests) > die("Can not allocate guest buffer"); > @@ -3002,6 +3046,19 @@ static char *parse_guest_name(char *guest, int *cid, int *port) > return guest; > } > > +int get_guest_vcpu_pid(unsigned int guest_cid, unsigned int guest_vcpu) > +{ > + int i; > + > + if (!guests || guest_vcpu >= VCPUS_MAX) > + return -1; > + > + for (i = 0; i < guests_len; i++) > + if (guest_cid == guests[i].cid) > + return guests[i].cpu_pid[guest_vcpu]; > + return -1; > +} > + > static void set_prio(int prio) > { > struct sched_param sp;