On 01/01/2025 18:27, Aurélien COUDERC wrote:
Here’s a quick « benchmark » in a sid Plasma desktop qemu VM where I had a
snapshot of up-to-date sid from Nov 24th, upgrading to today’s sid :
Summary:
Upgrading: 658, Installing: 304, Removing: 58, Not Upgrading: 2
Download size: 0 B / 1 032 MB
Space needed: 573 MB / 9 051 MB available
# time apt -y full-upgrade
real 9m49,143s
user 2m16,581s
sys 1m17,361s
# time eatmydata apt -y full-upgrade
real 3m25,268s
user 2m26,820s
sys 1m16,784s
That’s close to a *3 times faster* wall clock time when run with eatmydata.
The second upgrade hasn't been written back at all. For up to 30
seconds, if your machine loses power and for example grub.{cfg,efi} or
shim.efi was updated, you can't boot at all. Not to mention Kernel
panics still happen.
Surely, we can all agree dpkg should at least do a single 'sync' at the
end? Perhaps this would be a more realistic comparison?
# time (eatmydata apt -y full-upgrade; sync)
I wrote something to compare a single `dpkg --install`. This is on a
stable chroot where I downloaded 2 packages. Installing and purging
with/without eatmydata, but with an explicit sync.
`dpkg --install something; sync`
vs.
`eatmydata dpkg --install something; sync`
The two .debs were
-rw-r--r-- 1 root root 138K Jan 1 18:29 fdisk_2.38.1-5+deb12u2_amd64.deb
-rw-r--r-- 1 root root 12M Jan 1 18:29
firmware-amd-graphics_20230210-5_all.deb
Running on an OKish SSD:
Warmup... Timing dpkg with fdisk
.05 .04 .04
Warmup... Timing eatmydata dpkg with fdisk
.03 .02 .02
Warmup... Timing dpkg with firmware-amd-graphics
.46 .47 .45
Warmup... Timing eatmydata dpkg with firmware-amd-graphics
.63 .63 .67
Running on the slowest mechanical HDD I have:
Warmup... Timing dpkg with fdisk
.09 .08 .11
Warmup... Timing eatmydata dpkg with fdisk
.05 .05 .05
Warmup... Timing dpkg with firmware-amd-graphics
3.46 3.58 3.46
Warmup... Timing eatmydata dpkg with firmware-amd-graphics
2.95 2.99 3.06
Not sure why SSD with eatmydata takes longer, but eatmydata is faster
consistently on a mechanical, but still only a 15% improvement.
Script snippet here:
https://salsa.debian.org/-/snippets/765
--
Regards,
Ahmad
