+/*
+ * Given a latency, return the index of the corresponding bucket in
+ * the structure tracking percentiles.
+ *
+ * (1) find the group (and error bits) that the value (latency)
+ * belongs to by looking at its MSB. (2) find the bucket number in the
+ * group by looking at the index bits.
+ *
+ */
+static unsigned int plat_val_to_idx(unsigned int val)
+{
+ unsigned int msb, error_bits, base, offset, idx;
+
+ /* Find MSB starting from bit 0 */
+ if (val == 0)
+ msb = 0;
+ else
+ msb = (sizeof(val)*8) - __builtin_clz(val) - 1;
+
+ /*
+ * MSB <= (FIO_IO_U_PLAT_BITS-1), cannot be rounded off. Use
+ * all bits of the sample as index
+ */
+ if (msb <= FIO_IO_U_PLAT_BITS)
+ return val;
+
+ /* Compute the number of error bits to discard*/
+ error_bits = msb - FIO_IO_U_PLAT_BITS;
+
+ /* Compute the number of buckets before the group */
+ base = (error_bits + 1) << FIO_IO_U_PLAT_BITS;
+
+ /*
+ * Discard the error bits and apply the mask to find the
+ * index for the buckets in the group
+ */
+ offset = (FIO_IO_U_PLAT_VAL - 1) & (val >> error_bits);
+
+ /* Make sure the index does not exceed (array size - 1) */
+ idx = (base + offset) < (FIO_IO_U_PLAT_NR - 1)?
+ (base + offset) : (FIO_IO_U_PLAT_NR - 1);
+
+ return idx;
+}
+
+/*
+ * Convert the given index of the bucket array to the value
+ * represented by the bucket
+ */
+static unsigned int plat_idx_to_val(unsigned int idx)
+{
+ unsigned int error_bits, k, base;
+
+ assert(idx < FIO_IO_U_PLAT_NR);
+
+ /* MSB <= (FIO_IO_U_PLAT_BITS-1), cannot be rounded off. Use
+ * all bits of the sample as index */
+ if (idx < (FIO_IO_U_PLAT_VAL << 1) )
+ return idx;
+
+ /* Find the group and compute the minimum value of that group */
+ error_bits = (idx >> FIO_IO_U_PLAT_BITS) -1;
+ base = 1 << (error_bits + FIO_IO_U_PLAT_BITS);
+
+ /* Find its bucket number of the group */
+ k = idx % FIO_IO_U_PLAT_VAL;
+
+ /* Return the mean of the range of the bucket */
+ return base + ((k + 0.5) * (1 << error_bits));
+}
+
+static int double_cmp(const void *a, const void *b)
+{
+ const fio_fp64_t fa = *(const fio_fp64_t *) a;
+ const fio_fp64_t fb = *(const fio_fp64_t *) b;
+ int cmp = 0;
+
+ if (fa.u.f > fb.u.f)
+ cmp = 1;
+ else if (fa.u.f < fb.u.f)
+ cmp = -1;
+
+ return cmp;
+}
+
+unsigned int calc_clat_percentiles(unsigned int *io_u_plat, unsigned long nr,
+ fio_fp64_t *plist, unsigned int **output,
+ unsigned int *maxv, unsigned int *minv)
+{
+ unsigned long sum = 0;
+ unsigned int len, i, j = 0;
+ unsigned int oval_len = 0;
+ unsigned int *ovals = NULL;
+ int is_last;
+
+ *minv = -1U;
+ *maxv = 0;
+
+ len = 0;
+ while (len < FIO_IO_U_LIST_MAX_LEN && plist[len].u.f != 0.0)
+ len++;
+
+ if (!len)
+ return 0;
+
+ /*
+ * Sort the percentile list. Note that it may already be sorted if
+ * we are using the default values, but since it's a short list this
+ * isn't a worry. Also note that this does not work for NaN values.
+ */
+ if (len > 1)
+ qsort((void*)plist, len, sizeof(plist[0]), double_cmp);
+
+ /*
+ * Calculate bucket values, note down max and min values
+ */
+ is_last = 0;
+ for (i = 0; i < FIO_IO_U_PLAT_NR && !is_last; i++) {
+ sum += io_u_plat[i];
+ while (sum >= (plist[j].u.f / 100.0 * nr)) {
+ assert(plist[j].u.f <= 100.0);
+
+ if (j == oval_len) {
+ oval_len += 100;
+ ovals = realloc(ovals, oval_len * sizeof(unsigned int));
+ }
+
+ ovals[j] = plat_idx_to_val(i);
+ if (ovals[j] < *minv)
+ *minv = ovals[j];
+ if (ovals[j] > *maxv)
+ *maxv = ovals[j];
+
+ is_last = (j == len - 1);
+ if (is_last)
+ break;
+
+ j++;
+ }
+ }
+
+ *output = ovals;
+ return len;
+}
+
+/*
+ * Find and display the p-th percentile of clat
+ */
+static void show_clat_percentiles(unsigned int *io_u_plat, unsigned long nr,
+ fio_fp64_t *plist)
+{
+ unsigned int len, j = 0, minv, maxv;
+ unsigned int *ovals;
+ int is_last, scale_down;
+
+ len = calc_clat_percentiles(io_u_plat, nr, plist, &ovals, &maxv, &minv);
+ if (!len)
+ goto out;
+
+ /*
+ * We default to usecs, but if the value range is such that we
+ * should scale down to msecs, do that.
+ */
+ if (minv > 2000 && maxv > 99999) {
+ scale_down = 1;
+ log_info(" clat percentiles (msec):\n |");
+ } else {
+ scale_down = 0;
+ log_info(" clat percentiles (usec):\n |");
+ }
+
+ for (j = 0; j < len; j++) {
+ char fbuf[8];
+
+ /* for formatting */
+ if (j != 0 && (j % 4) == 0)
+ log_info(" |");
+
+ /* end of the list */
+ is_last = (j == len - 1);
+
+ if (plist[j].u.f < 10.0)
+ sprintf(fbuf, " %2.2f", plist[j].u.f);
+ else
+ sprintf(fbuf, "%2.2f", plist[j].u.f);
+
+ if (scale_down)
+ ovals[j] = (ovals[j] + 999) / 1000;
+
+ log_info(" %sth=[%5u]%c", fbuf, ovals[j], is_last ? '\n' : ',');
+
+ if (is_last)
+ break;
+
+ if (j % 4 == 3) /* for formatting */
+ log_info("\n");
+ }
+
+out:
+ if (ovals)
+ free(ovals);
+}
+
+int calc_lat(struct io_stat *is, unsigned long *min, unsigned long *max,
+ double *mean, double *dev)