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Description of problem:

The ktimersoftirq is waking up every time the timer interrupt takes place - even when there is no timer to be handled. This behavior is causing a problem of latency for the kvm-rt workload.

The solution to this problem is the integration of the upstream's -rt specific patch [1].

At the moment of the kvm-rt BZ (BZ1550584) report, I tested [1] upstream, and it worked fine. However, it depended on the timer wheel rework [2]. And so, I started backporting the timer wheel rework to the kernel-rt.

The timer wheel rework patch set is mostly done now, and it will be ready to be posted soon. However, bugs were found in [1], making it non-ready for the upstream -rt kernel, so we cannot integrate it in our kernel as well.

So we decided to split the BUG into two bugs:

The enhance BZ backporting the timer wheel rework (this one)
The BUG fix BZ, to integrate the final version of [1] #BZ1550584

[1] https://patchwork.kernel.org/patch/10263111/
[2] https://patchwork.kernel.org/patch/9183973/


Version-Release number of selected component (if applicable):
RHEL 7.5 kernel

Hi Jaroslav!

It is still accurate, thanks for the changes, looks better now!

-- Daniel

(In reply to Daniel Bristot de Oliveira from comment #11)
> Hi Jaroslav!
> 
> It is still accurate, thanks for the changes, looks better now!
> 
> -- Daniel

Thanks for your verification. By the way, I moved the "." back to the beginning. It is due to AsciiDoc markup, the title must start with a dot.

--Jaroslav

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2019:2043