Re: Performance issues with custom kernel and schedgraph tool

From: Mark Johnston <markj_at_freebsd.org>
Date: Thu, 23 Feb 2023 18:03:03 UTC
On Thu, Feb 23, 2023 at 09:19:36AM -0300, Nicolas Goldman wrote:
> Hello everyone,
> 
> I have recently been experiencing performance issues on my FreeBSD system,
> specifically with the task scheduler. I have* modified the scheduler (*I’m
> working on a short-term scheduler based on Petri Nets*)* and now see too
> much idle processor time. I have tried using the schedgraph tool to analyze
> the scheduler performance but I am receiving display errors.

What kind of display errors?

How are you collecting tracing info?  There are two ways, one with
dtrace and one with KTR.  Might be, your modifications to the scheduler
somehow changed or removed tracing events in a way that schedgraph
doesn't handle?

> I want to ask the community if anyone has experienced similar issues with
> the FreeBSD task scheduler, and if they have any advice or solutions for
> improving performance. Is there any way to use the schedgraph tool in
> non-GUI mode, as I am having trouble running it on my system without a
> graphical display?

I believe schedgraph.py is the only available visualization tool, so
you'd need to copy everything to a system with a grapical display.

> Any help or suggestions would be greatly appreciated. Thank you in advance
> for your assistance!
> 
> Best regards, Nico.