blktrace: Add support for sparse CPU numbers

[blktrace.git] / blktrace.c

diff --git a/blktrace.c b/blktrace.c
index b445524b1f0b8b38ae9d13f030d7cdf171558a78..f7d35dd1a62e4c687575314e77a6a6a75fcdcc83 100644 (file)
--- a/blktrace.c
+++ b/blktrace.c
@@ -274,7 +274,9 @@ static char blktrace_version[] = "2.0.0";
 int data_is_native = -1;
 
 static int ndevs;
+static int max_cpus;
 static int ncpus;
+static cpu_set_t *online_cpus;
 static int pagesize;
 static int act_mask = ~0U;
 static int kill_running_trace;
@@ -623,8 +625,9 @@ static int lock_on_cpu(int cpu)
 {
        cpu_set_t * cpu_mask;
        size_t size;
-       cpu_mask = CPU_ALLOC(ncpus);
-       size = CPU_ALLOC_SIZE(ncpus);
+
+       cpu_mask = CPU_ALLOC(max_cpus);
+       size = CPU_ALLOC_SIZE(max_cpus);
 
        CPU_ZERO_S(size, cpu_mask);
        CPU_SET_S(cpu, size, cpu_mask);
@@ -882,7 +885,7 @@ static int net_send_header(int fd, int cpu, char *buts_name, int len)
        strncpy(hdr.buts_name, buts_name, sizeof(hdr.buts_name));
        hdr.buts_name[sizeof(hdr.buts_name) - 1] = '\0';
        hdr.cpu = cpu;
-       hdr.max_cpus = ncpus;
+       hdr.max_cpus = max_cpus;
        hdr.len = len;
        hdr.cl_id = getpid();
        hdr.buf_size = buf_size;
@@ -1026,9 +1029,12 @@ static int net_setup_client(void)
 static int open_client_connections(void)
 {
        int cpu;
+       size_t alloc_size = CPU_ALLOC_SIZE(max_cpus);
 
        cl_fds = calloc(ncpus, sizeof(*cl_fds));
-       for (cpu = 0; cpu < ncpus; cpu++) {
+       for (cpu = 0; cpu < max_cpus; cpu++) {
+               if (!CPU_ISSET_S(cpu, alloc_size, online_cpus))
+                       continue;
                cl_fds[cpu] = net_setup_client();
                if (cl_fds[cpu] < 0)
                        goto err;
@@ -1046,8 +1052,11 @@ static void close_client_connections(void)
 {
        if (cl_fds) {
                int cpu, *fdp;
+               size_t alloc_size = CPU_ALLOC_SIZE(max_cpus);
 
-               for (cpu = 0, fdp = cl_fds; cpu < ncpus; cpu++, fdp++) {
+               for (cpu = 0, fdp = cl_fds; cpu < max_cpus; cpu++, fdp++) {
+                       if (!CPU_ISSET_S(cpu, alloc_size, online_cpus))
+                               continue;
                        if (*fdp >= 0) {
                                net_send_drops(*fdp);
                                net_close_connection(fdp);
@@ -1071,7 +1080,7 @@ static void setup_buts(void)
                buts.act_mask = act_mask;
 
                if (ioctl(dpp->fd, BLKTRACESETUP, &buts) >= 0) {
-                       dpp->ncpus = ncpus;
+                       dpp->ncpus = max_cpus;
                        dpp->buts_name = strdup(buts.name);
                        if (dpp->stats)
                                free(dpp->stats);
@@ -1155,7 +1164,7 @@ static void free_tracer_heads(struct devpath *dpp)
        int cpu;
        struct tracer_devpath_head *hd;
 
-       for (cpu = 0, hd = dpp->heads; cpu < ncpus; cpu++, hd++) {
+       for (cpu = 0, hd = dpp->heads; cpu < max_cpus; cpu++, hd++) {
                if (hd->prev)
                        free(hd->prev);
 
@@ -1177,8 +1186,8 @@ static int setup_tracer_devpaths(void)
                struct tracer_devpath_head *hd;
                struct devpath *dpp = list_entry(p, struct devpath, head);
 
-               dpp->heads = calloc(ncpus, sizeof(struct tracer_devpath_head));
-               for (cpu = 0, hd = dpp->heads; cpu < ncpus; cpu++, hd++) {
+               dpp->heads = calloc(max_cpus, sizeof(struct tracer_devpath_head));
+               for (cpu = 0, hd = dpp->heads; cpu < max_cpus; cpu++, hd++) {
                        INIT_LIST_HEAD(&hd->head);
                        pthread_mutex_init(&hd->mutex, NULL);
                        hd->prev = NULL;
@@ -1426,7 +1435,7 @@ static void __process_trace_bufs(void)
                struct devpath *dpp = list_entry(p, struct devpath, head);
                struct tracer_devpath_head *hd = dpp->heads;
 
-               for (cpu = 0; cpu < ncpus; cpu++, hd++) {
+               for (cpu = 0; cpu < max_cpus; cpu++, hd++) {
                        pthread_mutex_lock(&hd->mutex);
                        if (list_empty(&hd->head)) {
                                pthread_mutex_unlock(&hd->mutex);
@@ -1876,14 +1885,19 @@ static int start_tracer(int cpu)
 
 static void start_tracers(void)
 {
-       int cpu;
+       int cpu, started = 0;
        struct list_head *p;
+       size_t alloc_size = CPU_ALLOC_SIZE(max_cpus);
 
-       for (cpu = 0; cpu < ncpus; cpu++)
+       for (cpu = 0; cpu < max_cpus; cpu++) {
+               if (!CPU_ISSET_S(cpu, alloc_size, online_cpus))
+                       continue;
                if (start_tracer(cpu))
                        break;
+               started++;
+       }
 
-       wait_tracers_ready(cpu);
+       wait_tracers_ready(started);
 
        __list_for_each(p, &tracers) {
                struct tracer *tp = list_entry(p, struct tracer, head);
@@ -2657,15 +2671,83 @@ static int run_tracers(void)
        return 0;
 }
 
+static cpu_set_t *get_online_cpus(void)
+{
+       FILE *cpus;
+       cpu_set_t *set;
+       size_t alloc_size;
+       int cpuid, prevcpuid = -1;
+       char nextch;
+       int n, ncpu, curcpu = 0;
+       int *cpu_nums;
+
+       ncpu = sysconf(_SC_NPROCESSORS_CONF);
+       if (ncpu < 0)
+               return NULL;
+
+       cpu_nums = malloc(sizeof(int)*ncpu);
+       if (!cpu_nums) {
+               errno = ENOMEM;
+               return NULL;
+       }
+
+       /*
+        * There is no way to easily get maximum CPU number. So we have to
+        * parse the file first to find it out and then create appropriate
+        * cpuset
+        */
+       cpus = my_fopen("/sys/devices/system/cpu/online", "r");
+       for (;;) {
+               n = fscanf(cpus, "%d%c", &cpuid, &nextch);
+               if (n <= 0)
+                       break;
+               if (n == 2 && nextch == '-') {
+                       prevcpuid = cpuid;
+                       continue;
+               }
+               if (prevcpuid == -1)
+                       prevcpuid = cpuid;
+               while (prevcpuid <= cpuid) {
+                       /* More CPUs listed than configured? */
+                       if (curcpu >= ncpu) {
+                               errno = EINVAL;
+                               return NULL;
+                       }
+                       cpu_nums[curcpu++] = prevcpuid++;
+               }
+               prevcpuid = -1;
+       }
+       fclose(cpus);
+
+       ncpu = curcpu;
+       max_cpus = cpu_nums[ncpu - 1] + 1;
+
+       /* Now that we have maximum cpu number, create a cpuset */
+       set = CPU_ALLOC(max_cpus);
+       if (!set) {
+               errno = ENOMEM;
+               return NULL;
+       }
+       alloc_size = CPU_ALLOC_SIZE(max_cpus);
+       CPU_ZERO_S(alloc_size, set);
+
+       for (curcpu = 0; curcpu < ncpu; curcpu++)
+               CPU_SET_S(cpu_nums[curcpu], alloc_size, set);
+
+       free(cpu_nums);
+
+       return set;
+}
+
 int main(int argc, char *argv[])
 {
        int ret = 0;
 
        setlocale(LC_NUMERIC, "en_US");
        pagesize = getpagesize();
-       ncpus = sysconf(_SC_NPROCESSORS_ONLN);
-       if (ncpus < 0) {
-               fprintf(stderr, "sysconf(_SC_NPROCESSORS_ONLN) failed %d/%s\n",
+       online_cpus = get_online_cpus();
+       if (!online_cpus) {
+               fprintf(stderr, "cannot get online cpus %d/%s\n",
                        errno, strerror(errno));
                ret = 1;
                goto out;
@@ -2674,6 +2756,7 @@ int main(int argc, char *argv[])
                goto out;
        }
 
+       ncpus = CPU_COUNT_S(CPU_ALLOC_SIZE(max_cpus), online_cpus);
        if (ndevs > 1 && output_name && strcmp(output_name, "-") != 0) {
                fprintf(stderr, "-o not supported with multiple devices\n");
                ret = 1;