evhz usage

EVHZ Usage

EVHZ is a utility written by Ian Kelling for verifying the polling rate of mice. With a few minor changes we can use the same tool for other input devices.

My fork: https://github.com/geefr/evhz

Original Project URL: https://git.sr.ht/~iank/evhz

If you clone from the original URL, run the following

# By default evhz only handles mice-like devices, so we need to make some tweaks
# In short we need to remove the check that event.type is EV_REL or EV_ABS
# This little command should do this for you
sed -i 's/event.type == EV_REL || event.type == EV_ABS/1/g' evhz.c

Verifying the polling rate of any device

# First go grab a copy of evhz
git clone https://github.com/geefr/evhz.git

cd evhz

# Now run evhz. It should show some output any time an event happens, be it mouse movement or any button press
# evhz needs to run as root, so this will ask you for a password when run
./run

EVHZ will display a rate based on the time between 2 consecutive inputs, so in order to prove that your polling works you need to trigger 2 input events within 1ms of each other.

• Start spamming your input
• Jumps work well, as you just need 2 inputs very close together, just jump on all the arrows repeatedly
• If you see multiple lines printed containing the phrase 'Latest 1000hz' then congratulations! You don't have any polling issues on the device itself, move on to testing within Stepmania.
• If you don't see 1000Hz in the output, or it seems to be capped at 125Hz, 250Hz, or 500Hz then you've got some limit on the device's polling rate.