Bug 12490

Summary: Improve latency of IPFire systems
Product: IPFire Reporter: Michael Tremer <michael.tremer>
Component: ---Assignee: Michael Tremer <michael.tremer>
Status: CLOSED FIXED QA Contact:
Severity: - Unknown -    
Priority: - Unknown - CC: arne.fitzenreiter, peter.mueller
Version: 2   
Hardware: unspecified   
OS: Unspecified   
Bug Depends on:    
Bug Blocks: 12464    

Description Michael Tremer 2020-09-29 08:11:36 UTC 
We should reconfigure the kernel as follows:

* CONFIG_NO_HZ_FULL=y
* CONFIG_HZ=1000
* CONFIG_PREEMPT=y

This will make IPFire systems more responsive to any network events without any significant downsides. There will be some downsize in "throughput" which refers to memory bandwidth and L1 cache invalidation which won't be a problem for our application at all.

There is more about this here: https://www.kernel.org/doc/Documentation/timers/NO_HZ.txt
Comment 1 Arne.F 2021-03-01 18:53:48 UTC 
this is superseeded. we have changed it to CONFIG_HZ=100 and enabled PREEMPT__VOLUNTARY
Comment 2 Michael Tremer 2021-03-02 13:24:43 UTC 
(In reply to Arne.F from comment #1)
> this is superseeded. we have changed it to CONFIG_HZ=100 and enabled
> PREEMPT__VOLUNTARY

Yes, but this isn't even in testing and definitely not shipped.
Comment 3 Peter Müller 2021-09-04 10:24:01 UTC 
What is the status of this bug?
Comment 4 Michael Tremer 2021-09-04 11:44:14 UTC 
PREEMPT_VOLUNTARY has been shipped, but 1000 HZ hasn't been fully tested, yet:

> https://git.ipfire.org/?p=people/ms/ipfire-2.x.git;a=commitdiff;h=ec3f35777c33d51dc49368a08f36e9d8868a8d9c
Comment 5 Peter Müller 2021-10-23 11:39:28 UTC 
https://patchwork.ipfire.org/project/ipfire/list/?series=2331

This will be part of upcoming Core Update 161, hence I set this to MODIFIED.