stat: sum sync_stat before reassigning bool first

Currently, sum_stat(&dst->sync_stat, &src->sync_stat, first, false)
is called after the summing the stats on a per ddir level.

The for-loop that sums the stats on a per ddir level will reassign
bool first to false when unified_rw_rep is used.

This means that the call to sum_stat() for sync_stat will be called
with first == false, even when it is the first sync_stat being summed,
leading to incorrect sync_stat calculations when unified_rw_rep is used.

In order to ensure that sync_stat is not incorrectly affected by the
reassignment of first, move the sync_stat summing before the for-loop.

Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
Link: https://lore.kernel.org/r/20211215122557.95600-1-Niklas.Cassel@wdc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/stat.c b/stat.c
index 7e84058d9b911294956d0970e218cf97ea0a3344..ec44c79e0115f651ee9b83b4940788cb613048c9 100644 (file)
--- a/stat.c
+++ b/stat.c
@@ -2130,6 +2130,8 @@ void sum_thread_stats(struct thread_stat *dst, struct thread_stat *src,
 {
        int k, l, m;
 
+       sum_stat(&dst->sync_stat, &src->sync_stat, first, false);
+
        for (l = 0; l < DDIR_RWDIR_CNT; l++) {
                if (!(dst->unified_rw_rep == UNIFIED_MIXED)) {
                        sum_stat(&dst->clat_stat[l], &src->clat_stat[l], first, false);
@@ -2166,7 +2168,6 @@ void sum_thread_stats(struct thread_stat *dst, struct thread_stat *src,
                }
        }
 
-       sum_stat(&dst->sync_stat, &src->sync_stat, first, false);
        dst->usr_time += src->usr_time;
        dst->sys_time += src->sys_time;
        dst->ctx += src->ctx;