On Fri, 31 Jan 2020 14:10:59 +0200
"Tzvetomir Stoyanov (VMware)" <tz.stoyanov@xxxxxxxxx> wrote:
> From: Tzvetomir Stoyanov <tstoyanov@xxxxxxxxxx>
>
> 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@xxxxxxxxxx>
> ---
> tracecmd/include/trace-local.h | 2 ++
> tracecmd/trace-record.c | 54 ++++++++++++++++++++++++++++++++++
> 2 files changed, 56 insertions(+)
>
> diff --git a/tracecmd/include/trace-local.h b/tracecmd/include/trace-local.h
> index 29f2779..a5cf064 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 28fe31b..b479e91 100644
> --- a/tracecmd/trace-record.c
> +++ b/tracecmd/trace-record.c
> @@ -3031,10 +3031,12 @@ 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];
Although this is probably fine for the near future, I don't like
arbitrary limits that don't have to do with max sizes of the storage
unit (like max int).
Why is the cpu_pid a static array and not one that is allocated? We
could use realloc, couldn't we, in the loading of it?
-- Steve
> };
>
> static struct guest *guests;
> @@ -3052,6 +3054,43 @@ 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 &&
> + strncmp(buf, "CPU ", 4) == 0) {
> + vcpu = atoi(buf + 4);
> + if (vcpu >= 0 && vcpu < VCPUS_MAX)
> + guest->cpu_pid[vcpu] = atoi(entry->d_name);
> + }
> +
> + fclose(f);
> + }
> + free(buf);
> +}
> +
> static void read_qemu_guests(void)
> {
> static bool initialized;
> @@ -3115,6 +3154,8 @@ 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");
> @@ -3160,6 +3201,19 @@ 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;
|