| Message ID | 20190319155536.19381-7-tstoyanov@vmware.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | trace-cmd: Timetamps sync between host and guest machines, relying on vsock events. | expand |
On Tue, Mar 19, 2019 at 5:56 PM Tzvetomir Stoyanov <tstoyanov@vmware.com> wrote: > > 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 | 1 + > tracecmd/trace-record.c | 56 ++++++++++++++++++++++++++++++++++ > 2 files changed, 57 insertions(+) > > diff --git a/tracecmd/include/trace-local.h b/tracecmd/include/trace-local.h > index 8413054..62f5e47 100644 > --- a/tracecmd/include/trace-local.h > +++ b/tracecmd/include/trace-local.h > @@ -245,6 +245,7 @@ int tracecmd_local_cpu_count(void); > void tracecmd_set_clock(struct buffer_instance *instance); > void tracecmd_remove_instance(struct buffer_instance *instance); > > +int get_guest_vcpu_pid(unsigned int guest_cid, unsigned int guest_vcpu); > /* No longer in event-utils.h */ > void __noreturn die(const char *fmt, ...); /* Can be overriden */ > void *malloc_or_die(unsigned int size); /* Can be overridden */ > diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c > index 3950242..8c8e46f 100644 > --- a/tracecmd/trace-record.c > +++ b/tracecmd/trace-record.c > @@ -2746,10 +2746,12 @@ 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; > @@ -2767,6 +2769,45 @@ 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_t; > + char path[PATH_MAX]; > + unsigned int vcpu; Maybe keep vcpu signed int to avoid implicit conversion from assigning the result of atoi()? We check if it's negative right after this. > + char *buf = NULL; > + DIR *dir; > + FILE *ft; > + size_t n; Initialize n to zero before passing it to getline(). OTOH both glibc and musl handle getdelim()/getline() correctly when the first argument is NULL, disregarding the second. I still think it's clearer if n gets initialized. > + > + snprintf(path, sizeof(path), "/proc/%s/task", guest_task); > + dir = opendir(path); > + if (!dir) > + return; > + > + for (entry_t = readdir(dir); entry_t; entry_t = readdir(dir)) { Nit: `while ((entry = readdir(dir))) {` is more common throughout the code. > + if (!(entry_t->d_type == DT_DIR && is_digits(entry_t->d_name))) > + continue; > + > + snprintf(path, sizeof(path), "/proc/%s/task/%s/comm", > + guest_task, entry_t->d_name); > + ft = fopen(path, "r"); > + if (!ft) > + continue; > + if (getline(&buf, &n, ft) < 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_t->d_name); > + > +next: > + fclose(ft); > + } `buf` needs to get free()-ed after the loop ends. > +} > + > static void read_qemu_guests(void) > { > static bool initialized; > @@ -2828,6 +2869,8 @@ 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"); > @@ -2873,6 +2916,19 @@ 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; > -- > 2.20.1 >
On Tue, 19 Mar 2019 16:35:28 +0000 Slavomir Kaslev <kaslevs@vmware.com> wrote: > > + > > + snprintf(path, sizeof(path), "/proc/%s/task", guest_task); > > + dir = opendir(path); > > + if (!dir) > > + return; > > + > > + for (entry_t = readdir(dir); entry_t; entry_t = readdir(dir)) { > > Nit: `while ((entry = readdir(dir))) {` is more common throughout the code. Agreed. Although in a lot of cases I prefer for() over while(), in this case, when the initialization is identical to the next iteration, the while() is preferred. -- Steve
diff --git a/tracecmd/include/trace-local.h b/tracecmd/include/trace-local.h index 8413054..62f5e47 100644 --- a/tracecmd/include/trace-local.h +++ b/tracecmd/include/trace-local.h @@ -245,6 +245,7 @@ int tracecmd_local_cpu_count(void); void tracecmd_set_clock(struct buffer_instance *instance); void tracecmd_remove_instance(struct buffer_instance *instance); +int get_guest_vcpu_pid(unsigned int guest_cid, unsigned int guest_vcpu); /* No longer in event-utils.h */ void __noreturn die(const char *fmt, ...); /* Can be overriden */ void *malloc_or_die(unsigned int size); /* Can be overridden */ diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c index 3950242..8c8e46f 100644 --- a/tracecmd/trace-record.c +++ b/tracecmd/trace-record.c @@ -2746,10 +2746,12 @@ 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; @@ -2767,6 +2769,45 @@ 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_t; + char path[PATH_MAX]; + unsigned int vcpu; + char *buf = NULL; + DIR *dir; + FILE *ft; + size_t n; + + snprintf(path, sizeof(path), "/proc/%s/task", guest_task); + dir = opendir(path); + if (!dir) + return; + + for (entry_t = readdir(dir); entry_t; entry_t = readdir(dir)) { + if (!(entry_t->d_type == DT_DIR && is_digits(entry_t->d_name))) + continue; + + snprintf(path, sizeof(path), "/proc/%s/task/%s/comm", + guest_task, entry_t->d_name); + ft = fopen(path, "r"); + if (!ft) + continue; + if (getline(&buf, &n, ft) < 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_t->d_name); + +next: + fclose(ft); + } +} + static void read_qemu_guests(void) { static bool initialized; @@ -2828,6 +2869,8 @@ 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"); @@ -2873,6 +2916,19 @@ 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;
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 | 1 + tracecmd/trace-record.c | 56 ++++++++++++++++++++++++++++++++++ 2 files changed, 57 insertions(+)