| Message ID | 20200227142001.61577-4-tz.stoyanov@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Timestamp synchronization of host - guest tracing session | expand |
On Thu, 27 Feb 2020 16:19:49 +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 | 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;
On Thu, Feb 27, 2020 at 7:23 PM Steven Rostedt <rostedt@goodmis.org> wrote: > > On Thu, 27 Feb 2020 16:19:49 +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 | 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. > The reason I use long is strtol(), which returns long integer. In case of an error, this API returns LONG_MAX or LONG_MIN. The set_vcpu_pid_mapping() accepts int, that's why I put these checks - to filter possible strtol() parsing errors and int overflow. I'll keep the checks and remove the duplicated ones in set_vcpu_pid_mapping() > > + 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? I'll put a warning, as this failure is not critical - the guest tracing will still work, even without this mapping. Thanks, Steven! > > > + > > 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; > -- Tzvetomir (Ceco) Stoyanov VMware Open Source Technology Center
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; + if (cpu >= guest->cpu_max) { + cpu_pid = realloc(guest->cpu_pid, (cpu + 1) * sizeof(int)); + if (!cpu_pid) + return -1; + 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) +{ + struct dirent *entry; + char path[PATH_MAX]; + char *buf = NULL; + size_t n = 0; + long int vcpu; + long int pid; + 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) + set_vcpu_pid_mapping(guest, vcpu, pid); + } + + 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); + 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) + 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;