Memcpy benchmark - possible irregularities?

I’m not sure what’s going on, because I somehow messed up the log files…

But can you please run a simple command for me, if possible on different kernels that you might have installed?

time perf bench -f simple mem memcpy --nr_loops 100 --size 2GB -f x86-64-movsb

I have seen a large increase that happened some time over the last 3 weeks, and I want to know if it was me who messed up something (highly probable) or a recent kernel update.
Please also report you CPU+RAM configuration.

Thanks :hugs:

real	0m28.654s
user	0m30.117s
sys	     0m0.930s

linux-ck 5.9.2-1-ck
Intel Xeon E3-1225-v3
24 GB RAM

I can reboot into a different kernel if it would help; would you prefer mainline Arch or LTS? Or both?

1 Like

It’s fine, don’t spend too much time on it.
I’m just trying to debug as I’m not happy with the results…
(22 real seconds here on 3900X - a month ago it was 17 seconds)

2 Likes
real|0m24,220s
user|0m23,322s
sys|0m0,829s

Amd X570-aorus-pro with 3600XT on 16Gb ( DDR3000 )

Not seeing this command working - what is it trying to do? Command not found…

1 Like

Probably needs some package installed.

I expect so - just don’t know what…

1 Like

sudo pacman -S perf
Sorry, I thought it came preinstalled.

1 Like

Ahh - I took a quick look with yay, to see what it might be called - but it might have been part of some other package…

Anyway -

real	0m24.955s
user	0m23.951s
sys	0m0.952s

I still don’t know what it does - but that’s how long it takes! :grin:

Oh - and for reference - Ryzen 7 3700x (with a few other things loaded)

Edit: It appears to max out 1 core only, and blip a couple of others near the end…

1 Like
real 0m22.877s
user 0m21.977s
sys 0m0.853s

Ryzen 3800X
32 GB Memory DDR4 3200 Mhz
MSI X570 Gaming Plus

1 Like

Zen
real 0m19.821s
user 0m19.354s
sys 0m0.403s
[elloquin@elloquin-elloquin ~]$

Mainline
real 0m24.018s
user 0m22.878s
sys 0m1.077s
[elloquin@elloquin-elloquin ~]$

LTS
real 0m23.276s
user 0m22.388s
sys 0m0.839s
[elloquin@elloquin-elloquin ~]$

Makes sense the zen kernel is supposed to have memory optimizations. Clean boot after closing welcome app.
1800x@4.0Ghz 32GB 3200 ram Crosshair VI

1 Like

A simple memcpy() of 2 GB using movsb instruction, run 100 times :slight_smile:

Thanks everyone!
It seems that the results are indeed within normal range.
I will mark this as solved :slight_smile:

PS: perf is a super useful tool for analysing system performance.
perf stat and perf top are two further interesting commands.

1 Like