On Thu, Feb 27, 2020 at 6:13 AM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>
> 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?
>
I did it to simplify the PoC implementation and never changed it to be
a dynamic array,
I'll reimplement it now.
Thanks Steven!
> -- 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;
>
--
Tzvetomir (Ceco) Stoyanov
VMware Open Source Technology Center
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