[PATCH] t/zbd: Fix I/O bytes rounding errors

[PATCH] t/zbd: Fix I/O bytes rounding errors

[Shin'ichiro Kawasaki]

When fio reports write bytes or read bytes, it rounds the number with
units MiB or KiB to fit the number within limited number of digits.
This results in rounding errors of the reported bytes and sometimes
causes test failures for test case #17 in test-zbd-support
which reports incorrect total I/O bytes in case both of write bytes
and read bytes are rounded up.

To avoid the rounding error, increase the number of digits from default
value 4 to 10 to keep precision. For example, a number "256MiB" will be
reported as "267911168B" with this change.

Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
---
 t/zbd/test-zbd-support | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/t/zbd/test-zbd-support b/t/zbd/test-zbd-support
index 10c78e9a..6fb48ef0 100755
--- a/t/zbd/test-zbd-support
+++ b/t/zbd/test-zbd-support
@@ -85,7 +85,8 @@ run_fio() {
 
     fio=$(dirname "$0")/../../fio
 
-    opts=("--aux-path=/tmp" "--allow_file_create=0" "$@")
+    opts=("--aux-path=/tmp" "--allow_file_create=0" \
+			    "--significant_figures=10" "$@")
     { echo; echo "fio ${opts[*]}"; echo; } >>"${logfile}.${test_number}"
 
     "${dynamic_analyzer[@]}" "$fio" "${opts[@]}"
-- 
2.21.0

Re: [PATCH] t/zbd: Fix I/O bytes rounding errors

[Jens Axboe]

On 8/8/19 8:28 PM, Shin'ichiro Kawasaki wrote:
> When fio reports write bytes or read bytes, it rounds the number with
> units MiB or KiB to fit the number within limited number of digits.
> This results in rounding errors of the reported bytes and sometimes
> causes test failures for test case #17 in test-zbd-support
> which reports incorrect total I/O bytes in case both of write bytes
> and read bytes are rounded up.
> 
> To avoid the rounding error, increase the number of digits from default
> value 4 to 10 to keep precision. For example, a number "256MiB" will be
> reported as "267911168B" with this change.

Thanks, applied.

-- 
Jens Axboe