samples: bpf: Driver interrupt statistics in xdpsock

Add an option to count the number of interrupts generated per second and
total number of interrupts during the lifetime of the application for a
given interface. This information is extracted from /proc/interrupts. Since
there is no naming convention across drivers, the user must provide the
string which is specific to their interface in the /proc/interrupts file on
the command line.

Usage:

./xdpsock ... -I <irq_str>

eg. for queue 0 of i40e device eth0:

./xdpsock ... -I i40e-eth0-TxRx-0

Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201002133612.31536-3-ciara.loftus@intel.com

diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c
index ff119ede4ab19e526d43fcf29dd803165eb8d272..1149e94ca32fd341954304de30beaa5082d6a91d 100644 (file)
--- a/samples/bpf/xdpsock_user.c
+++ b/samples/bpf/xdpsock_user.c
@@ -11,6 +11,7 @@
 #include <linux/if_xdp.h>
 #include <linux/if_ether.h>
 #include <linux/ip.h>
+#include <linux/limits.h>
 #include <linux/udp.h>
 #include <arpa/inet.h>
 #include <locale.h>
@@ -80,6 +81,9 @@ static u32 opt_pkt_fill_pattern = 0x12345678;
 static bool opt_extra_stats;
 static bool opt_quiet;
 static bool opt_app_stats;
+static const char *opt_irq_str = "";
+static u32 irq_no;
+static int irqs_at_init = -1;
 static int opt_poll;
 static int opt_interval = 1;
 static u32 opt_xdp_bind_flags = XDP_USE_NEED_WAKEUP;
@@ -111,6 +115,11 @@ struct xsk_ring_stats {
        unsigned long prev_tx_empty_npkts;
 };
 
+struct xsk_driver_stats {
+       unsigned long intrs;
+       unsigned long prev_intrs;
+};
+
 struct xsk_app_stats {
        unsigned long rx_empty_polls;
        unsigned long fill_fail_polls;
@@ -138,6 +147,7 @@ struct xsk_socket_info {
        struct xsk_socket *xsk;
        struct xsk_ring_stats ring_stats;
        struct xsk_app_stats app_stats;
+       struct xsk_driver_stats drv_stats;
        u32 outstanding_tx;
 };
 
@@ -243,6 +253,100 @@ static void dump_app_stats(long dt)
        }
 }
 
+static bool get_interrupt_number(void)
+{
+       FILE *f_int_proc;
+       char line[4096];
+       bool found = false;
+
+       f_int_proc = fopen("/proc/interrupts", "r");
+       if (f_int_proc == NULL) {
+               printf("Failed to open /proc/interrupts.\n");
+               return found;
+       }
+
+       while (!feof(f_int_proc) && !found) {
+               /* Make sure to read a full line at a time */
+               if (fgets(line, sizeof(line), f_int_proc) == NULL ||
+                               line[strlen(line) - 1] != '\n') {
+                       printf("Error reading from interrupts file\n");
+                       break;
+               }
+
+               /* Extract interrupt number from line */
+               if (strstr(line, opt_irq_str) != NULL) {
+                       irq_no = atoi(line);
+                       found = true;
+                       break;
+               }
+       }
+
+       fclose(f_int_proc);
+
+       return found;
+}
+
+static int get_irqs(void)
+{
+       char count_path[PATH_MAX];
+       int total_intrs = -1;
+       FILE *f_count_proc;
+       char line[4096];
+
+       snprintf(count_path, sizeof(count_path),
+               "/sys/kernel/irq/%i/per_cpu_count", irq_no);
+       f_count_proc = fopen(count_path, "r");
+       if (f_count_proc == NULL) {
+               printf("Failed to open %s\n", count_path);
+               return total_intrs;
+       }
+
+       if (fgets(line, sizeof(line), f_count_proc) == NULL ||
+                       line[strlen(line) - 1] != '\n') {
+               printf("Error reading from %s\n", count_path);
+       } else {
+               static const char com[2] = ",";
+               char *token;
+
+               total_intrs = 0;
+               token = strtok(line, com);
+               while (token != NULL) {
+                       /* sum up interrupts across all cores */
+                       total_intrs += atoi(token);
+                       token = strtok(NULL, com);
+               }
+       }
+
+       fclose(f_count_proc);
+
+       return total_intrs;
+}
+
+static void dump_driver_stats(long dt)
+{
+       int i;
+
+       for (i = 0; i < num_socks && xsks[i]; i++) {
+               char *fmt = "%-18s %'-14.0f %'-14lu\n";
+               double intrs_ps;
+               int n_ints = get_irqs();
+
+               if (n_ints < 0) {
+                       printf("error getting intr info for intr %i\n", irq_no);
+                       return;
+               }
+               xsks[i]->drv_stats.intrs = n_ints - irqs_at_init;
+
+               intrs_ps = (xsks[i]->drv_stats.intrs - xsks[i]->drv_stats.prev_intrs) *
+                        1000000000. / dt;
+
+               printf("\n%-18s %-14s %-14s\n", "", "intrs/s", "count");
+               printf(fmt, "irqs", intrs_ps, xsks[i]->drv_stats.intrs);
+
+               xsks[i]->drv_stats.prev_intrs = xsks[i]->drv_stats.intrs;
+       }
+}
+
 static void dump_stats(void)
 {
        unsigned long now = get_nsecs();
@@ -327,6 +431,8 @@ static void dump_stats(void)
 
        if (opt_app_stats)
                dump_app_stats(dt);
+       if (irq_no)
+               dump_driver_stats(dt);
 }
 
 static bool is_benchmark_done(void)
@@ -804,6 +910,7 @@ static struct option long_options[] = {
        {"extra-stats", no_argument, 0, 'x'},
        {"quiet", no_argument, 0, 'Q'},
        {"app-stats", no_argument, 0, 'a'},
+       {"irq-string", no_argument, 0, 'I'},
        {0, 0, 0, 0}
 };
 
@@ -841,6 +948,7 @@ static void usage(const char *prog)
                "  -x, --extra-stats    Display extra statistics.\n"
                "  -Q, --quiet          Do not display any stats.\n"
                "  -a, --app-stats      Display application (syscall) statistics.\n"
+               "  -I, --irq-string     Display driver interrupt statistics for interface associated with irq-string.\n"
                "\n";
        fprintf(stderr, str, prog, XSK_UMEM__DEFAULT_FRAME_SIZE,
                opt_batch_size, MIN_PKT_SIZE, MIN_PKT_SIZE,
@@ -856,7 +964,7 @@ static void parse_command_line(int argc, char **argv)
        opterr = 0;
 
        for (;;) {
-               c = getopt_long(argc, argv, "Frtli:q:pSNn:czf:muMd:b:C:s:P:xQa",
+               c = getopt_long(argc, argv, "Frtli:q:pSNn:czf:muMd:b:C:s:P:xQaI:",
                                long_options, &option_index);
                if (c == -1)
                        break;
@@ -945,6 +1053,16 @@ static void parse_command_line(int argc, char **argv)
                        break;
                case 'a':
                        opt_app_stats = 1;
+                       break;
+               case 'I':
+                       opt_irq_str = optarg;
+                       if (get_interrupt_number())
+                               irqs_at_init = get_irqs();
+                       if (irqs_at_init < 0) {
+                               fprintf(stderr, "ERROR: Failed to get irqs for %s\n", opt_irq_str);
+                               usage(basename(argv[0]));
+                       }
+
                        break;
                default:
                        usage(basename(argv[0]));