Subject: Re: [bug#41720] [PATCH] store: Use buffered I/O for all protocol writes
From: Ludovic Courtès <[email-masked]>
To: Lars-Dominik Braun <[email-masked]>
Cc: [email-masked]
Date: Tue, 09 Jun 2020 09:49:49 +0200
List-Id: <debbugs-submit.debbugs.gnu.org>

Hi!

Lars-Dominik Braun <[email-masked]> skribis:

>> Nice, though the slowdown on Unix-domain sockets is annoying given that
>> it’s the primary transport.  Are the 10% significant and stable over
>> multiple runs?
> I don’t want to blind your eyes with meaningless statistics here, but let’s do
> this properly then. So for `guix environment guix -- true` with 10 trials these
> are the results:
>
> ---snip---
> $ ministat -A -c 99 before_ssh after_ssh
> x before_ssh
> + after_ssh
>     N           Min           Max        Median           Avg        Stddev
> x  10          7.63        10.635       10.1585        9.9382    0.85517585
> +  10         5.986         6.424        6.1755        6.1917    0.15398416
> Difference at 99.0% confidence
>         -3.7465 +/- 0.790815
>         -37.698% +/- 5.0788%
>         (Student's t, pooled s = 0.614425)
>
> $ ministat -A -c 99 before_unix after_unix
> x before_unix
> + after_unix
>     N           Min           Max        Median           Avg        Stddev
> x  10         1.528         1.624        1.5445        1.5636   0.035842867
> +  10         1.576         1.701        1.6145        1.6229   0.037869513
> Difference at 99.0% confidence
>         0.0593 +/- 0.0474548
>         3.79253% +/- 3.08989%
>         (Student's t, pooled s = 0.0368701)
> ---snap---
>
> And the same for `guix environment --ad-hoc r-learnr`:
>
> ---snip---
> $ ministat -A -c 99 before_ssh after_ssh
> x before_ssh
> + after_ssh
>     N           Min           Max        Median           Avg        Stddev
> x  10        20.104        21.629        21.082       21.0115    0.45142472
> +  10        16.082        16.713        16.292       16.3416    0.25018224
> Difference at 99.0% confidence
>         -4.6699 +/- 0.469719
>         -22.2254% +/- 1.86734%
>         (Student's t, pooled s = 0.364949)
>
> $ ministat -A -c 99 before_unix after_unix
> x before_unix
> + after_unix
>     N           Min           Max        Median           Avg        Stddev
> x  10        11.322        11.529        11.401       11.4127   0.062467858
> +  10        11.249        11.469       11.3515        11.368   0.078689262
> No difference proven at 99.0% confidence
> ---snap---

Awesome, thanks a lot.  Looks like the difference on Unix-domain sockets
is not significant.

Applied!

What package provides ‘ministat’?

Thanks,
Ludo’.