Add completion percentiles to results output
[fio.git] / stat.c
diff --git a/stat.c b/stat.c
index 83ffd06..40ca1d3 100644 (file)
--- a/stat.c
+++ b/stat.c
@@ -9,7 +9,7 @@
 
 #include "fio.h"
 #include "diskutil.h"
-#include "ieee754.h"
+#include "lib/ieee754.h"
 
 void update_rusage_stat(struct thread_data *td)
 {
@@ -114,23 +114,25 @@ static int double_cmp(const void *a, const void *b)
        return cmp;
 }
 
-/*
- * 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 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, minv = -1U, maxv = 0;
-       unsigned int *ovals = NULL, oval_len = 0;
-       int is_last, scale_down;
+       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;
+               return 0;
 
        /*
         * Sort the percentile list. Note that it may already be sorted if
@@ -155,10 +157,10 @@ static void show_clat_percentiles(unsigned int *io_u_plat, unsigned long nr,
                        }
 
                        ovals[j] = plat_idx_to_val(i);
-                       if (ovals[j] < minv)
-                               minv = ovals[j];
-                       if (ovals[j] > maxv)
-                               maxv = ovals[j];
+                       if (ovals[j] < *minv)
+                               *minv = ovals[j];
+                       if (ovals[j] > *maxv)
+                               *maxv = ovals[j];
 
                        is_last = (j == len - 1);
                        if (is_last)
@@ -168,6 +170,24 @@ static void show_clat_percentiles(unsigned int *io_u_plat, unsigned long nr,
                }
        }
 
+       *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.
@@ -207,12 +227,13 @@ static void show_clat_percentiles(unsigned int *io_u_plat, unsigned long nr,
                        log_info("\n");
        }
 
+out:
        if (ovals)
                free(ovals);
 }
 
-static int calc_lat(struct io_stat *is, unsigned long *min, unsigned long *max,
-                   double *mean, double *dev)
+int calc_lat(struct io_stat *is, unsigned long *min, unsigned long *max,
+            double *mean, double *dev)
 {
        double n = is->samples;
 
@@ -239,7 +260,7 @@ void show_group_stats(struct group_run_stats *rs)
        const char *ddir_str[] = { "   READ", "  WRITE" };
        int i;
 
-       log_info("Run status group %d (all jobs):\n", rs->groupid);
+       log_info("\nRun status group %d (all jobs):\n", rs->groupid);
 
        for (i = 0; i <= DDIR_WRITE; i++) {
                const int i2p = is_power_of_2(rs->kb_base);
@@ -316,18 +337,23 @@ static void stat_calc_lat_m(struct thread_stat *ts, double *io_u_lat)
        stat_calc_lat(ts, io_u_lat, ts->io_u_lat_m, FIO_IO_U_LAT_M_NR);
 }
 
-static int usec_to_msec(unsigned long *min, unsigned long *max, double *mean,
-                       double *dev)
+static void display_lat(const char *name, unsigned long min, unsigned long max,
+                       double mean, double dev)
 {
-       if (*min > 1000 && *max > 1000 && *mean > 1000.0 && *dev > 1000.0) {
-               *min /= 1000;
-               *max /= 1000;
-               *mean /= 1000.0;
-               *dev /= 1000.0;
-               return 0;
-       }
+       const char *base = "(usec)";
+       char *minp, *maxp;
 
-       return 1;
+       if (!usec_to_msec(&min, &max, &mean, &dev))
+               base = "(msec)";
+
+       minp = num2str(min, 6, 1, 0);
+       maxp = num2str(max, 6, 1, 0);
+
+       log_info("    %s %s: min=%s, max=%s, avg=%5.02f,"
+                " stdev=%5.02f\n", name, base, minp, maxp, mean, dev);
+
+       free(minp);
+       free(maxp);
 }
 
 static void show_ddir_status(struct group_run_stats *rs, struct thread_stat *ts,
@@ -363,81 +389,55 @@ static void show_ddir_status(struct group_run_stats *rs, struct thread_stat *ts,
        free(bw_p);
        free(iops_p);
 
-       if (calc_lat(&ts->slat_stat[ddir], &min, &max, &mean, &dev)) {
-               const char *base = "(usec)";
-               char *minp, *maxp;
-
-               if (!usec_to_msec(&min, &max, &mean, &dev))
-                       base = "(msec)";
-
-               minp = num2str(min, 6, 1, 0);
-               maxp = num2str(max, 6, 1, 0);
-
-               log_info("    slat %s: min=%s, max=%s, avg=%5.02f,"
-                        " stdev=%5.02f\n", base, minp, maxp, mean, dev);
-
-               free(minp);
-               free(maxp);
-       }
-       if (calc_lat(&ts->clat_stat[ddir], &min, &max, &mean, &dev)) {
-               const char *base = "(usec)";
-               char *minp, *maxp;
-
-               if (!usec_to_msec(&min, &max, &mean, &dev))
-                       base = "(msec)";
-
-               minp = num2str(min, 6, 1, 0);
-               maxp = num2str(max, 6, 1, 0);
-
-               log_info("    clat %s: min=%s, max=%s, avg=%5.02f,"
-                        " stdev=%5.02f\n", base, minp, maxp, mean, dev);
-
-               free(minp);
-               free(maxp);
-       }
-       if (calc_lat(&ts->lat_stat[ddir], &min, &max, &mean, &dev)) {
-               const char *base = "(usec)";
-               char *minp, *maxp;
-
-               if (!usec_to_msec(&min, &max, &mean, &dev))
-                       base = "(msec)";
-
-               minp = num2str(min, 6, 1, 0);
-               maxp = num2str(max, 6, 1, 0);
-
-               log_info("     lat %s: min=%s, max=%s, avg=%5.02f,"
-                        " stdev=%5.02f\n", base, minp, maxp, mean, dev);
+       if (calc_lat(&ts->slat_stat[ddir], &min, &max, &mean, &dev))
+               display_lat("slat", min, max, mean, dev);
+       if (calc_lat(&ts->clat_stat[ddir], &min, &max, &mean, &dev))
+               display_lat("clat", min, max, mean, dev);
+       if (calc_lat(&ts->lat_stat[ddir], &min, &max, &mean, &dev))
+               display_lat(" lat", min, max, mean, dev);
 
-               free(minp);
-               free(maxp);
-       }
        if (ts->clat_percentiles) {
                show_clat_percentiles(ts->io_u_plat[ddir],
                                        ts->clat_stat[ddir].samples,
                                        ts->percentile_list);
        }
        if (calc_lat(&ts->bw_stat[ddir], &min, &max, &mean, &dev)) {
-               double p_of_agg;
+               double p_of_agg = 100.0;
+               const char *bw_str = "KB";
 
-               p_of_agg = mean * 100 / (double) rs->agg[ddir];
-               log_info("     bw (KB/s) : min=%5lu, max=%5lu, per=%3.2f%%,"
-                        " avg=%5.02f, stdev=%5.02f\n", min, max, p_of_agg,
-                                                       mean, dev);
+               if (rs->agg[ddir]) {
+                       p_of_agg = mean * 100 / (double) rs->agg[ddir];
+                       if (p_of_agg > 100.0)
+                               p_of_agg = 100.0;
+               }
+
+               if (mean > 999999.9) {
+                       min /= 1000.0;
+                       max /= 1000.0;
+                       mean /= 1000.0;
+                       dev /= 1000.0;
+                       bw_str = "MB";
+               }
+
+               log_info("    bw (%s/s)  : min=%5lu, max=%5lu, per=%3.2f%%,"
+                        " avg=%5.02f, stdev=%5.02f\n", bw_str, min, max,
+                                                       p_of_agg, mean, dev);
        }
 }
 
-static void show_lat(double *io_u_lat, int nr, const char **ranges,
-                    const char *msg)
+static int show_lat(double *io_u_lat, int nr, const char **ranges,
+                   const char *msg)
 {
-       int new_line = 1, i, line = 0;
+       int new_line = 1, i, line = 0, shown = 0;
 
        for (i = 0; i < nr; i++) {
                if (io_u_lat[i] <= 0.0)
                        continue;
+               shown = 1;
                if (new_line) {
                        if (line)
                                log_info("\n");
-                       log_info("     lat (%s): ", msg);
+                       log_info("    lat (%s) : ", msg);
                        new_line = 0;
                        line = 0;
                }
@@ -448,6 +448,11 @@ static void show_lat(double *io_u_lat, int nr, const char **ranges,
                if (line == 5)
                        new_line = 1;
        }
+
+       if (shown)
+               log_info("\n");
+
+       return shown;
 }
 
 static void show_lat_u(double *io_u_lat_u)
@@ -467,12 +472,14 @@ static void show_lat_m(double *io_u_lat_m)
        show_lat(io_u_lat_m, FIO_IO_U_LAT_M_NR, ranges, "msec");
 }
 
-static void show_latencies(double *io_u_lat_u, double *io_u_lat_m)
+static void show_latencies(struct thread_stat *ts, double *io_u_lat_u,
+                          double *io_u_lat_m)
 {
+       stat_calc_lat_u(ts, io_u_lat_u);
+       stat_calc_lat_m(ts, io_u_lat_m);
+
        show_lat_u(io_u_lat_u);
-       log_info("\n");
        show_lat_m(io_u_lat_m);
-       log_info("\n");
 }
 
 void show_thread_status(struct thread_stat *ts, struct group_run_stats *rs)
@@ -497,7 +504,7 @@ void show_thread_status(struct thread_stat *ts, struct group_run_stats *rs)
                                        ts->error, ts->verror, (int) ts->pid);
        }
 
-       if (ts->description)
+       if (strlen(ts->description))
                log_info("  Description  : [%s]\n", ts->description);
 
        if (ts->io_bytes[DDIR_READ])
@@ -505,6 +512,8 @@ void show_thread_status(struct thread_stat *ts, struct group_run_stats *rs)
        if (ts->io_bytes[DDIR_WRITE])
                show_ddir_status(rs, ts, DDIR_WRITE);
 
+       show_latencies(ts, io_u_lat_u, io_u_lat_m);
+
        runtime = ts->total_run_time;
        if (runtime) {
                double runt = (double) runtime;
@@ -538,14 +547,12 @@ void show_thread_status(struct thread_stat *ts, struct group_run_stats *rs)
                                        io_u_dist[1], io_u_dist[2],
                                        io_u_dist[3], io_u_dist[4],
                                        io_u_dist[5], io_u_dist[6]);
-       log_info("     issued r/w/d: total=%lu/%lu/%lu, short=%lu/%lu/%lu\n",
+       log_info("     issued    : total=r=%lu/w=%lu/d=%lu,"
+                                " short=r=%lu/w=%lu/d=%lu\n",
                                        ts->total_io_u[0], ts->total_io_u[1],
                                        ts->total_io_u[2],
                                        ts->short_io_u[0], ts->short_io_u[1],
                                        ts->short_io_u[2]);
-       stat_calc_lat_u(ts, io_u_lat_u);
-       stat_calc_lat_m(ts, io_u_lat_m);
-       show_latencies(io_u_lat_u, io_u_lat_m);
        if (ts->continue_on_error) {
                log_info("     errors    : total=%lu, first_error=%d/<%s>\n",
                                        ts->total_err_count,
@@ -558,16 +565,23 @@ static void show_ddir_status_terse(struct thread_stat *ts,
                                   struct group_run_stats *rs, int ddir)
 {
        unsigned long min, max;
-       unsigned long long bw;
+       unsigned long long bw, iops;
+       unsigned int *ovals = NULL;
        double mean, dev;
+       unsigned int len, minv, maxv;
+       int i;
 
        assert(ddir_rw(ddir));
 
-       bw = 0;
-       if (ts->runtime[ddir])
-               bw = ts->io_bytes[ddir] / ts->runtime[ddir];
+       iops = bw = 0;
+       if (ts->runtime[ddir]) {
+               uint64_t runt = ts->runtime[ddir];
 
-       log_info(";%llu;%llu;%llu", ts->io_bytes[ddir] >> 10, bw,
+               bw = ts->io_bytes[ddir] / runt;
+               iops = (1000 * (uint64_t) ts->total_io_u[ddir]) / runt;
+       }
+
+       log_info(";%llu;%llu;%llu;%llu", ts->io_bytes[ddir] >> 10, bw, iops,
                                                        ts->runtime[ddir]);
 
        if (calc_lat(&ts->slat_stat[ddir], &min, &max, &mean, &dev))
@@ -580,24 +594,46 @@ static void show_ddir_status_terse(struct thread_stat *ts,
        else
                log_info(";%lu;%lu;%f;%f", 0UL, 0UL, 0.0, 0.0);
 
+       if (ts->clat_percentiles) {
+               len = calc_clat_percentiles(ts->io_u_plat[ddir],
+                                       ts->clat_stat[ddir].samples,
+                                       ts->percentile_list, &ovals, &maxv,
+                                       &minv);
+       } else
+               len = 0;
+
+       for (i = 0; i < FIO_IO_U_LIST_MAX_LEN; i++) {
+               if (i >= len) {
+                       log_info(";0%%=0");
+                       continue;
+               }
+               log_info(";%2.2f%%=%u", ts->percentile_list[i].u.f, ovals[i]);
+       }
+
        if (calc_lat(&ts->lat_stat[ddir], &min, &max, &mean, &dev))
                log_info(";%lu;%lu;%f;%f", min, max, mean, dev);
        else
                log_info(";%lu;%lu;%f;%f", 0UL, 0UL, 0.0, 0.0);
 
+       if (ovals)
+               free(ovals);
+
        if (calc_lat(&ts->bw_stat[ddir], &min, &max, &mean, &dev)) {
-               double p_of_agg;
+               double p_of_agg = 100.0;
+
+               if (rs->agg[ddir]) {
+                       p_of_agg = mean * 100 / (double) rs->agg[ddir];
+                       if (p_of_agg > 100.0)
+                               p_of_agg = 100.0;
+               }
 
-               p_of_agg = mean * 100 / (double) rs->agg[ddir];
                log_info(";%lu;%lu;%f%%;%f;%f", min, max, p_of_agg, mean, dev);
        } else
                log_info(";%lu;%lu;%f%%;%f;%f", 0UL, 0UL, 0.0, 0.0, 0.0);
 }
 
-#define FIO_TERSE_VERSION      "2"
-
-static void show_thread_status_terse(struct thread_stat *ts,
-                                    struct group_run_stats *rs)
+static void show_thread_status_terse_v2(struct thread_stat *ts,
+                                       struct group_run_stats *rs)
 {
        double io_u_dist[FIO_IO_U_MAP_NR];
        double io_u_lat_u[FIO_IO_U_LAT_U_NR];
@@ -606,8 +642,7 @@ static void show_thread_status_terse(struct thread_stat *ts,
        int i;
 
        /* General Info */
-       log_info("%s;%s;%d;%d", FIO_TERSE_VERSION, ts->name, ts->groupid,
-                               ts->error);
+       log_info("2;%s;%d;%d", ts->name, ts->groupid, ts->error);
        /* Log Read Status */
        show_ddir_status_terse(ts, rs, 0);
        /* Log Write Status */
@@ -655,6 +690,80 @@ static void show_thread_status_terse(struct thread_stat *ts,
        log_info("\n");
 }
 
+#define FIO_TERSE_VERSION      "3"
+
+static void show_thread_status_terse_v3(struct thread_stat *ts,
+                                       struct group_run_stats *rs)
+{
+       double io_u_dist[FIO_IO_U_MAP_NR];
+       double io_u_lat_u[FIO_IO_U_LAT_U_NR];
+       double io_u_lat_m[FIO_IO_U_LAT_M_NR];
+       double usr_cpu, sys_cpu;
+       int i;
+
+       /* General Info */
+       log_info("%s;%s;%s;%d;%d", FIO_TERSE_VERSION, fio_version_string,
+                                       ts->name, ts->groupid, ts->error);
+       /* Log Read Status */
+       show_ddir_status_terse(ts, rs, 0);
+       /* Log Write Status */
+       show_ddir_status_terse(ts, rs, 1);
+
+       /* CPU Usage */
+       if (ts->total_run_time) {
+               double runt = (double) ts->total_run_time;
+
+               usr_cpu = (double) ts->usr_time * 100 / runt;
+               sys_cpu = (double) ts->sys_time * 100 / runt;
+       } else {
+               usr_cpu = 0;
+               sys_cpu = 0;
+       }
+
+       log_info(";%f%%;%f%%;%lu;%lu;%lu", usr_cpu, sys_cpu, ts->ctx, ts->majf,
+                                                               ts->minf);
+
+       /* Calc % distribution of IO depths, usecond, msecond latency */
+       stat_calc_dist(ts->io_u_map, ts_total_io_u(ts), io_u_dist);
+       stat_calc_lat_u(ts, io_u_lat_u);
+       stat_calc_lat_m(ts, io_u_lat_m);
+
+       /* Only show fixed 7 I/O depth levels*/
+       log_info(";%3.1f%%;%3.1f%%;%3.1f%%;%3.1f%%;%3.1f%%;%3.1f%%;%3.1f%%",
+                       io_u_dist[0], io_u_dist[1], io_u_dist[2], io_u_dist[3],
+                       io_u_dist[4], io_u_dist[5], io_u_dist[6]);
+
+       /* Microsecond latency */
+       for (i = 0; i < FIO_IO_U_LAT_U_NR; i++)
+               log_info(";%3.2f%%", io_u_lat_u[i]);
+       /* Millisecond latency */
+       for (i = 0; i < FIO_IO_U_LAT_M_NR; i++)
+               log_info(";%3.2f%%", io_u_lat_m[i]);
+
+       /* disk util stats, if any */
+       show_disk_util(1);
+
+       /* Additional output if continue_on_error set - default off*/
+       if (ts->continue_on_error)
+               log_info(";%lu;%d", ts->total_err_count, ts->first_error);
+       log_info("\n");
+
+       /* Additional output if description is set */
+       if (strlen(ts->description))
+               log_info(";%s", ts->description);
+}
+
+static void show_thread_status_terse(struct thread_stat *ts,
+                                    struct group_run_stats *rs)
+{
+       if (terse_version == 2)
+               show_thread_status_terse_v2(ts, rs);
+       else if (terse_version == 3)
+               show_thread_status_terse_v3(ts, rs);
+       else
+               log_err("fio: bad terse version!? %d\n", terse_version);
+}
+
 static void sum_stat(struct io_stat *dst, struct io_stat *src, int nr)
 {
        double mean, S;
@@ -944,25 +1053,23 @@ void show_run_stats(void)
                        show_thread_status(ts, rs);
        }
 
-       if (!terse_output) {
-               for (i = 0; i < groupid + 1; i++) {
-                       rs = &runstats[i];
-
-                       rs->groupid = i;
-                       if (is_backend)
-                               fio_server_send_gs(rs);
-                       else
-                               show_group_stats(rs);
-               }
+       for (i = 0; i < groupid + 1; i++) {
+               rs = &runstats[i];
 
+               rs->groupid = i;
                if (is_backend)
-                       fio_server_send_du();
-               else
-                       show_disk_util();
-
-               free_disk_util();
+                       fio_server_send_gs(rs);
+               else if (!terse_output)
+                       show_group_stats(rs);
        }
 
+       if (is_backend)
+               fio_server_send_du();
+       else if (!terse_output)
+               show_disk_util(0);
+
+       free_disk_util();
+
        free(runstats);
        free(threadstats);
 }
@@ -992,6 +1099,9 @@ static void __add_log_sample(struct io_log *iolog, unsigned long val,
 {
        const int nr_samples = iolog->nr_samples;
 
+       if (!iolog->nr_samples)
+               iolog->avg_last = t;
+
        if (iolog->nr_samples == iolog->max_samples) {
                int new_size = sizeof(struct io_sample) * iolog->max_samples*2;
 
@@ -1006,14 +1116,66 @@ static void __add_log_sample(struct io_log *iolog, unsigned long val,
        iolog->nr_samples++;
 }
 
+static inline void reset_io_stat(struct io_stat *ios)
+{
+       ios->max_val = ios->min_val = ios->samples = 0;
+       ios->mean.u.f = ios->S.u.f = 0;
+}
+
 static void add_log_sample(struct thread_data *td, struct io_log *iolog,
                           unsigned long val, enum fio_ddir ddir,
                           unsigned int bs)
 {
+       unsigned long elapsed, this_window;
+
        if (!ddir_rw(ddir))
                return;
 
-       __add_log_sample(iolog, val, ddir, bs, mtime_since_now(&td->epoch));
+       elapsed = mtime_since_now(&td->epoch);
+
+       /*
+        * If no time averaging, just add the log sample.
+        */
+       if (!iolog->avg_msec) {
+               __add_log_sample(iolog, val, ddir, bs, elapsed);
+               return;
+       }
+
+       /*
+        * Add the sample. If the time period has passed, then
+        * add that entry to the log and clear.
+        */
+       add_stat_sample(&iolog->avg_window[ddir], val);
+
+       /*
+        * If period hasn't passed, adding the above sample is all we
+        * need to do.
+        */
+       this_window = elapsed - iolog->avg_last;
+       if (this_window < iolog->avg_msec)
+               return;
+
+       /*
+        * Note an entry in the log. Use the mean from the logged samples,
+        * making sure to properly round up. Only write a log entry if we
+        * had actual samples done.
+        */
+       if (iolog->avg_window[DDIR_READ].samples) {
+               unsigned long mr;
+
+               mr = iolog->avg_window[DDIR_READ].mean.u.f + 0.50;
+               __add_log_sample(iolog, mr, DDIR_READ, 0, elapsed);
+       }
+       if (iolog->avg_window[DDIR_WRITE].samples) {
+               unsigned long mw;
+
+               mw = iolog->avg_window[DDIR_WRITE].mean.u.f + 0.50;
+               __add_log_sample(iolog, mw, DDIR_WRITE, 0, elapsed);
+       }
+
+       reset_io_stat(&iolog->avg_window[DDIR_READ]);
+       reset_io_stat(&iolog->avg_window[DDIR_WRITE]);
+       iolog->avg_last = elapsed;
 }
 
 void add_agg_sample(unsigned long val, enum fio_ddir ddir, unsigned int bs)
@@ -1094,15 +1256,26 @@ void add_bw_sample(struct thread_data *td, enum fio_ddir ddir, unsigned int bs,
        if (spent < td->o.bw_avg_time)
                return;
 
-       rate = (td->this_io_bytes[ddir] - td->stat_io_bytes[ddir]) *
-                       1000 / spent / 1024;
-       add_stat_sample(&ts->bw_stat[ddir], rate);
+       /*
+        * Compute both read and write rates for the interval.
+        */
+       for (ddir = DDIR_READ; ddir <= DDIR_WRITE; ddir++) {
+               uint64_t delta;
+
+               delta = td->this_io_bytes[ddir] - td->stat_io_bytes[ddir];
+               if (!delta)
+                       continue; /* No entries for interval */
+
+               rate = delta * 1000 / spent / 1024;
+               add_stat_sample(&ts->bw_stat[ddir], rate);
 
-       if (td->bw_log)
-               add_log_sample(td, td->bw_log, rate, ddir, bs);
+               if (td->bw_log)
+                       add_log_sample(td, td->bw_log, rate, ddir, bs);
+
+               td->stat_io_bytes[ddir] = td->this_io_bytes[ddir];
+       }
 
        fio_gettime(&td->bw_sample_time, NULL);
-       td->stat_io_bytes[ddir] = td->this_io_bytes[ddir];
 }
 
 void add_iops_sample(struct thread_data *td, enum fio_ddir ddir,
@@ -1118,15 +1291,24 @@ void add_iops_sample(struct thread_data *td, enum fio_ddir ddir,
        if (spent < td->o.iops_avg_time)
                return;
 
-       iops = ((td->this_io_blocks[ddir] - td->stat_io_blocks[ddir]) * 1000) / spent;
+       /*
+        * Compute both read and write rates for the interval.
+        */
+       for (ddir = DDIR_READ; ddir <= DDIR_WRITE; ddir++) {
+               uint64_t delta;
+
+               delta = td->this_io_blocks[ddir] - td->stat_io_blocks[ddir];
+               if (!delta)
+                       continue; /* No entries for interval */
+
+               iops = (delta * 1000) / spent;
+               add_stat_sample(&ts->iops_stat[ddir], iops);
 
-       add_stat_sample(&ts->iops_stat[ddir], iops);
+               if (td->iops_log)
+                       add_log_sample(td, td->iops_log, iops, ddir, 0);
 
-       if (td->iops_log) {
-               assert(iops);
-               add_log_sample(td, td->iops_log, iops, ddir, 0);
+               td->stat_io_blocks[ddir] = td->this_io_blocks[ddir];
        }
 
        fio_gettime(&td->iops_sample_time, NULL);
-       td->stat_io_blocks[ddir] = td->this_io_blocks[ddir];
 }