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=-8.3 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 BE7F2C11D3D for ; Thu, 27 Feb 2020 17:23:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A204F246A2 for ; Thu, 27 Feb 2020 17:23:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729800AbgB0RXG (ORCPT ); Thu, 27 Feb 2020 12:23:06 -0500 Received: from mail.kernel.org ([198.145.29.99]:44270 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728413AbgB0RXF (ORCPT ); Thu, 27 Feb 2020 12:23:05 -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 CC483246A0; Thu, 27 Feb 2020 17:23:04 +0000 (UTC) Date: Thu, 27 Feb 2020 12:23:03 -0500 From: Steven Rostedt To: "Tzvetomir Stoyanov (VMware)" Cc: linux-trace-devel@vger.kernel.org Subject: Re: [PATCH v20 03/15] trace-cmd: Find and store pids of tasks, which run virtual CPUs of given VM Message-ID: <20200227122303.25dacb7b@gandalf.local.home> In-Reply-To: <20200227142001.61577-4-tz.stoyanov@gmail.com> References: <20200227142001.61577-1-tz.stoyanov@gmail.com> <20200227142001.61577-4-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 Thu, 27 Feb 2020 16:19:49 +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 | 77 ++++++++++++++++++++++++++++++++++ > 2 files changed, 79 insertions(+) > > diff --git a/tracecmd/include/trace-local.h b/tracecmd/include/trace-local.h > index 29f27793..a5cf0640 100644 > --- a/tracecmd/include/trace-local.h > +++ b/tracecmd/include/trace-local.h > @@ -247,6 +247,8 @@ 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 28fe31b7..4370c964 100644 > --- a/tracecmd/trace-record.c > +++ b/tracecmd/trace-record.c > @@ -3035,11 +3035,30 @@ struct guest { > char *name; > int cid; > int pid; > + int cpu_max; > + int *cpu_pid; > }; > > static struct guest *guests; > static size_t guests_len; > > +static int set_vcpu_pid_mapping(struct guest *guest, int cpu, int pid) > +{ > + int *cpu_pid; > + > + if (cpu < 0 || pid < 0) > + return -1; This check makes the check before its call not needed (see below). > + if (cpu >= guest->cpu_max) { > + cpu_pid = realloc(guest->cpu_pid, (cpu + 1) * sizeof(int)); It is possible that the cpu numbers may be sparse, which means we should we should probably initialize the new numbers as... > + if (!cpu_pid) > + return -1; /* Handle sparse CPU numbers */ for (i = guest->cpu_max; i < cpu; i++) guest->cpu_pid[i] = -1; Note, the above wont loop at all if there's no sparse CPUs (missing numbers). > + guest->cpu_max = cpu + 1; > + guest->cpu_pid = cpu_pid; > + } > + guest->cpu_pid[cpu] = pid; > + return 0; > +} > + > static char *get_qemu_guest_name(char *arg) > { > char *tok, *end = arg; > @@ -3052,6 +3071,46 @@ static char *get_qemu_guest_name(char *arg) > return arg; > } > > +static void read_qemu_guests_pids(char *guest_task, struct guest *guest) Probably should return a status. > +{ > + struct dirent *entry; > + char path[PATH_MAX]; > + char *buf = NULL; > + size_t n = 0; > + long int vcpu; > + long int pid; "int" is not needed. Just "long" is good enough. long vcpu; long pid; Although, I doubt there will be more than 4 billion of either of these, so they should probably be just "int". Which means you don't need the INT_MAX checks. > + 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 && > + strncmp(buf, "CPU ", 4) == 0) { > + vcpu = strtol(buf + 4, NULL, 10); > + pid = strtol(entry->d_name, NULL, 10); > + if (vcpu < INT_MAX && pid < INT_MAX && > + vcpu >= 0 && pid >= 0) The vcpu >= 0 && pid >= 0 are not needed due to the check in the function. > + set_vcpu_pid_mapping(guest, vcpu, pid); Probably should check the return status of this function, and report a warning if it fails. > + } > + > + fclose(f); > + } > + free(buf); > +} > + > static void read_qemu_guests(void) > { > static bool initialized; > @@ -3115,6 +3174,8 @@ static void read_qemu_guests(void) > if (!is_qemu) > goto next; > > + read_qemu_guests_pids(entry->d_name, &guest); Should probably check the status of the above function. Die on error? > + > guests = realloc(guests, (guests_len + 1) * sizeof(*guests)); > if (!guests) > die("Can not allocate guest buffer"); > @@ -3160,6 +3221,22 @@ 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) > + return -1; > + > + for (i = 0; i < guests_len; i++) { > + if (!guests[i].cpu_pid || guest_vcpu >= guests[i].cpu_max) As a cpu_pid may be zero (unlikely), and the code I showed above initialized sparse cpus as -1, then this should be guests[i].cpu_pid < 0. -- Steve > + continue; > + 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;