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Re: [PATCH v7 18/21] simplebench/results_to_text: improve view of the ta

From: Vladimir Sementsov-Ogievskiy
Subject: Re: [PATCH v7 18/21] simplebench/results_to_text: improve view of the table
Date: Fri, 13 Nov 2020 19:24:05 +0300
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.1

13.11.2020 18:59, Max Reitz wrote:
On 21.10.20 16:58, Vladimir Sementsov-Ogievskiy wrote:
Move to generic format for floats and percentage for error.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
  scripts/simplebench/results_to_text.py | 13 ++++++++++++-
  1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/scripts/simplebench/results_to_text.py 
index 58d909ffd9..479f7ac1d4 100644
--- a/scripts/simplebench/results_to_text.py
+++ b/scripts/simplebench/results_to_text.py
@@ -16,11 +16,22 @@
  # along with this program.  If not, see <http://www.gnu.org/licenses/>.
+import math
+def format_value(x, stdev):
+    stdev_pr = stdev / x * 100
+    if stdev_pr < 1.5:
+        # don't care too much
+        return f'{x:.2g}'
+    else:
+        return f'{x:.2g} ± {math.ceil(stdev_pr)}%'

OK, so no magnitude-based precision this time (except for the %f -> %g change). 
 Works for me.

Other than that, I personally don’t like the relative standard deviation much, 
because the absolute SD immediately shows the 68 % boundaries (and an idea on 
the 95 % boundaries with 2σ), whereas the RSD just gives an impression on how 
spread out the data is.  (Which I find the absolute SD also does, when given 
together with the average, which is the case here.)

I realized that for myself, the only thing I need from +-deviation is a kind of 
"reliability" of the result. And it's more obvious for me in percentage. 
Looking at the table with a lot of numbers, where most of values have deviation less than 
+-5%, some values with deviation +-30 would catch the eye immediately. And with absolute 
SD I have to look through the table more carefully.

To be completely honest, though, I didn’t even know the term “relative SD” 
existed until a couple of minutes ago, and I didn’t know it was something that 
was used at all.
And if I haven’t seen the RSD used in practice, I can’t confidently say that I 
have good reasons not to like it.

But, well, I can’t have any confidence in liking it either, and because the 
change from ASD to RSD is basically the most important change of this patch 
(which I can’t really agree is an improvement), I can’t really give an R-b.

Perhaps this is OK:

Acked-by: Max Reitz <mreitz@redhat.com>


I don't have strict opinion about how this should look. For now these scripts 
don't have wide usage... We can always add an option to adjust table view, and 
I will not mind making absolute SD the default view.

Best regards,

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