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DescriptionMarcelo Tosatti
2019-07-15 15:14:36 UTC
RHEL-7.8 RT will include a feature to skip ktimersoftd wakeup.
This feature is disabled by default and requires writing
1 to /sys/kernel/ktimer_lockless_check.
This should be enabled for tuned realtime profile.
Do I understand it correctly that the sysfs file does not exist in the RHEL-7.7 realtime kernel, but is going to exist in the RHEL-7.8 RT kernel? What about RHEL-8? I'm just wondering whether we should put this change upstream or RHEL-7.8 only.
(In reply to Ondřej Lysoněk from comment #2)
> Do I understand it correctly that the sysfs file does not exist in the
> RHEL-7.7 realtime kernel, but is going to exist in the RHEL-7.8 RT kernel?
> What about RHEL-8? I'm just wondering whether we should put this change
> upstream or RHEL-7.8 only.
Its already upstream:
https://github.com/redhat-performance/tuned/commit/25089296f312281502dbb3689cb24eb24c48ffeb
So all is necessary is to backport it to RHEL-7.8 (and include it in RHEL-8 as well).
Business justification (customer impact; how would the defect impact customers’ business? why is it not possible to wait for a fix in Y-Stream?):
This fix is necessary for the current NFV deployment with
Altiostar to achieve the required latency.
How many customers are impacted by this defect?
Right now it is only Altiostar, but they could deploy it
more customers in the coming weeks.
When was the defect introduced in this major version of RHEL? Is it a regression?
What is the minimal patch set to fix this bug? (link, git commit,...)
(In reply to Luiz Capitulino from comment #8)
> Business justification (customer impact; how would the defect impact
> customers’ business? why is it not possible to wait for a fix in Y-Stream?):
>
> This fix is necessary for the current NFV deployment with
> Altiostar to achieve the required latency.
Hi Luiz.
Can you please elaborate on what is the impact of not achieving the required latency? Especially in the situation without this fix.
Thanks.
Comment 10Jaroslav Škarvada
2020-03-25 17:27:09 UTC
(In reply to Luiz Capitulino from comment #8)
> Business justification (customer impact; how would the defect impact
> customers’ business? why is it not possible to wait for a fix in Y-Stream?):
>
> This fix is necessary for the current NFV deployment with
> Altiostar to achieve the required latency.
>
> How many customers are impacted by this defect?
>
> Right now it is only Altiostar, but they could deploy it
> more customers in the coming weeks.
>
> When was the defect introduced in this major version of RHEL? Is it a
> regression?
>
It's for the backported kernel patch. It's not regression.
>
>
> What is the minimal patch set to fix this bug? (link, git commit,...)
>
https://github.com/redhat-performance/tuned/commit/25089296f312281502dbb3689cb24eb24c48ffeb
(In reply to Tomáš Hozza from comment #9)
> (In reply to Luiz Capitulino from comment #8)
> > Business justification (customer impact; how would the defect impact
> > customers’ business? why is it not possible to wait for a fix in Y-Stream?):
> >
> > This fix is necessary for the current NFV deployment with
> > Altiostar to achieve the required latency.
>
> Hi Luiz.
>
> Can you please elaborate on what is the impact of not achieving the required
> latency? Especially in the situation without this fix.
We may loose some telco businesses.
The NFV field team has made a RT OSP deployment that's been
used by some telco companies to evaluate our solution for NFV.
This deployment was having latency spikes, which means the
current evaluation is failing. We debugged it down and this
BZ is one of the fixes necessary for 7.7.z in order to make
the evaluation pass.
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/RHBA-2020:1008