return ret != 10;
}
+static uint64_t safe_32bit_diff(uint64_t nval, uint64_t oval)
+{
+ /* Linux kernel prints some of the stat fields as 32-bit integers. It is
+ * possible that the value overflows, but since fio uses unsigned 64-bit
+ * arithmetic in update_io_tick_disk(), it instead results in a huge
+ * bogus value being added to the respective accumulating field. Just
+ * in case Linux starts reporting these metrics as 64-bit values in the
+ * future, check that overflow actually happens around the 32-bit
+ * unsigned boundary; assume overflow only happens once between
+ * successive polls.
+ */
+ if (oval <= nval || oval >= (1ull << 32))
+ return nval - oval;
+ else
+ return (1ull << 32) + nval - oval;
+}
+
static void update_io_tick_disk(struct disk_util *du)
{
struct disk_util_stat __dus, *dus, *ldus;
dus->s.ios[1] += (__dus.s.ios[1] - ldus->s.ios[1]);
dus->s.merges[0] += (__dus.s.merges[0] - ldus->s.merges[0]);
dus->s.merges[1] += (__dus.s.merges[1] - ldus->s.merges[1]);
- dus->s.ticks[0] += (__dus.s.ticks[0] - ldus->s.ticks[0]);
- dus->s.ticks[1] += (__dus.s.ticks[1] - ldus->s.ticks[1]);
- dus->s.io_ticks += (__dus.s.io_ticks - ldus->s.io_ticks);
- dus->s.time_in_queue += (__dus.s.time_in_queue - ldus->s.time_in_queue);
+ dus->s.ticks[0] += safe_32bit_diff(__dus.s.ticks[0], ldus->s.ticks[0]);
+ dus->s.ticks[1] += safe_32bit_diff(__dus.s.ticks[1], ldus->s.ticks[1]);
+ dus->s.io_ticks += safe_32bit_diff(__dus.s.io_ticks, ldus->s.io_ticks);
+ dus->s.time_in_queue +=
+ safe_32bit_diff(__dus.s.time_in_queue, ldus->s.time_in_queue);
fio_gettime(&t, NULL);
dus->s.msec += mtime_since(&du->time, &t);
- memcpy(&du->time, &t, sizeof(t));
- memcpy(&ldus->s, &__dus.s, sizeof(__dus.s));
+ du->time = t;
+ ldus->s = __dus.s;
}
int update_io_ticks(void)