iocost: improve nr_lagging handling

[linux-2.6-microblaze.git] / block / blk-iocost.c

diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 32d4d6d..10160de 100644 (file)
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -1407,7 +1407,8 @@ static void ioc_timer_fn(struct timer_list *timer)
                 * comparing vdone against period start.  If lagging behind
                 * IOs from past periods, don't increase vrate.
                 */
-               if (!atomic_read(&iocg_to_blkg(iocg)->use_delay) &&
+               if ((ppm_rthr != MILLION || ppm_wthr != MILLION) &&
+                   !atomic_read(&iocg_to_blkg(iocg)->use_delay) &&
                    time_after64(vtime, vdone) &&
                    time_after64(vtime, now.vnow -
                                 MAX_LAGGING_PERIODS * period_vtime) &&
@@ -1537,21 +1538,23 @@ skip_surplus_transfers:
            missed_ppm[WRITE] > ppm_wthr) {
                ioc->busy_level = max(ioc->busy_level, 0);
                ioc->busy_level++;
-       } else if (nr_lagging) {
-               ioc->busy_level = max(ioc->busy_level, 0);
-       } else if (nr_shortages && !nr_surpluses &&
-                  rq_wait_pct <= RQ_WAIT_BUSY_PCT * UNBUSY_THR_PCT / 100 &&
+       } else if (rq_wait_pct <= RQ_WAIT_BUSY_PCT * UNBUSY_THR_PCT / 100 &&
                   missed_ppm[READ] <= ppm_rthr * UNBUSY_THR_PCT / 100 &&
                   missed_ppm[WRITE] <= ppm_wthr * UNBUSY_THR_PCT / 100) {
-               ioc->busy_level = min(ioc->busy_level, 0);
-               ioc->busy_level--;
+               /* take action iff there is contention */
+               if (nr_shortages && !nr_lagging) {
+                       ioc->busy_level = min(ioc->busy_level, 0);
+                       /* redistribute surpluses first */
+                       if (!nr_surpluses)
+                               ioc->busy_level--;
+               }
        } else {
                ioc->busy_level = 0;
        }
 
        ioc->busy_level = clamp(ioc->busy_level, -1000, 1000);
 
-       if (ioc->busy_level) {
+       if (ioc->busy_level > 0 || (ioc->busy_level < 0 && !nr_lagging)) {
                u64 vrate = atomic64_read(&ioc->vtime_rate);
                u64 vrate_min = ioc->vrate_min, vrate_max = ioc->vrate_max;