From: Steven Rostedt <rostedt@goodmis.org>
To: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>
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
Date: Wed, 4 Dec 2019 16:35:56 -0500 [thread overview]
Message-ID: <20191204163556.197cc4f3@gandalf.local.home> (raw)
In-Reply-To: <20191203103522.482684-8-tz.stoyanov@gmail.com>
On Tue, 3 Dec 2019 12:35:11 +0200
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> wrote:
> From: Tzvetomir Stoyanov <tstoyanov@vmware.com>
>
> 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 <tstoyanov@vmware.com>
> ---
> 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;
next prev parent reply other threads:[~2019-12-04 21:36 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-03 10:35 [PATCH v17 00/18]Timestamp synchronization of host - guest tracing session Tzvetomir Stoyanov (VMware)
2019-12-03 10:35 ` [PATCH v17 01/18] trace-cmd: Implement new lib API: tracecmd_local_events_system() Tzvetomir Stoyanov (VMware)
2019-12-03 10:35 ` [PATCH v17 02/18] trace-cmd: Add support for negative time offsets in trace.dat file Tzvetomir Stoyanov (VMware)
2019-12-03 10:35 ` [PATCH v17 03/18] trace-cmd: Add implementations of htonll() and ntohll() Tzvetomir Stoyanov (VMware)
2019-12-20 13:50 ` Steven Rostedt
2020-01-06 14:30 ` Tzvetomir Stoyanov
2019-12-03 10:35 ` [PATCH v17 04/18] trace-cmd: Add new library APIs for ftrace instances Tzvetomir Stoyanov (VMware)
2019-12-04 16:17 ` Steven Rostedt
2019-12-05 14:40 ` Tzvetomir Stoyanov
2019-12-03 10:35 ` [PATCH v17 05/18] trace-cmd: Add new library API for local CPU count Tzvetomir Stoyanov (VMware)
2019-12-04 20:09 ` Steven Rostedt
2019-12-03 10:35 ` [PATCH v17 06/18] trace-cmd: Add new library API for reading ftrace buffers Tzvetomir Stoyanov (VMware)
2019-12-04 21:10 ` Steven Rostedt
2019-12-03 10:35 ` [PATCH v17 07/18] trace-cmd: Find and store pids of tasks, which run virtual CPUs of given VM Tzvetomir Stoyanov (VMware)
2019-12-04 21:35 ` Steven Rostedt [this message]
2019-12-03 10:35 ` [PATCH v17 08/18] trace-cmd: Implement new API tracecmd_add_option_v() Tzvetomir Stoyanov (VMware)
2019-12-04 21:47 ` Steven Rostedt
2019-12-03 10:35 ` [PATCH v17 09/18] trace-cmd: Add new API to generate a unique ID of the tracing session Tzvetomir Stoyanov (VMware)
2019-12-03 10:35 ` [PATCH v17 10/18] trace-cmd: Store the session tracing ID in the trace.dat file Tzvetomir Stoyanov (VMware)
2019-12-03 10:35 ` [PATCH v17 11/18] trace-cmd: Exchange tracing IDs between host and guest Tzvetomir Stoyanov (VMware)
2019-12-04 22:03 ` Steven Rostedt
2019-12-03 10:35 ` [PATCH v17 12/18] trace-cmd: Implement new option in trace.dat file: TRACECMD_OPTION_TIME_SHIFT Tzvetomir Stoyanov (VMware)
2019-12-05 0:46 ` Steven Rostedt
2019-12-05 15:09 ` Tzvetomir Stoyanov
2019-12-03 10:35 ` [PATCH v17 13/18] trace-cmd: Add guest information in host's trace.dat file Tzvetomir Stoyanov (VMware)
2019-12-05 0:59 ` Steven Rostedt
2019-12-03 10:35 ` [PATCH v17 14/18] trace-cmd: Add host trace clock as guest trace argument Tzvetomir Stoyanov (VMware)
2019-12-09 19:31 ` Steven Rostedt
2019-12-10 8:49 ` Tzvetomir Stoyanov
2019-12-10 15:48 ` Steven Rostedt
2019-12-11 8:21 ` Tzvetomir Stoyanov
2019-12-11 15:01 ` Steven Rostedt
2019-12-03 10:35 ` [PATCH v17 15/18] trace-cmd: Refactor few trace-cmd internal functions Tzvetomir Stoyanov (VMware)
2019-12-09 19:32 ` Steven Rostedt
2019-12-03 10:35 ` [PATCH v17 16/18] trace-cmd: Basic infrastructure for host - guest timestamp synchronization Tzvetomir Stoyanov (VMware)
2019-12-10 17:04 ` Steven Rostedt
2019-12-10 18:39 ` Steven Rostedt
2019-12-12 12:34 ` Tzvetomir Stoyanov
2019-12-12 14:54 ` Steven Rostedt
2019-12-12 14:00 ` Tzvetomir Stoyanov
2019-12-03 10:35 ` [PATCH v17 17/18] trace-cmd: [POC] PTP-like algorithm " Tzvetomir Stoyanov (VMware)
2019-12-03 10:35 ` [PATCH v17 18/18] trace-cmd: Debug scripts for " Tzvetomir Stoyanov (VMware)
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