netdev - Re: Re: EEVDF/vhost regression (bisected to 86bfbb7ce4f6 sched/fair: Add lag based placement)

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Message-ID: <ZVyt4UU9+XxunIP7@DESKTOP-2CCOB1S.>
Date: Tue, 21 Nov 2023 14:17:21 +0100
From: Tobias Huschle <huschle@...ux.ibm.com>
To: Abel Wu <wuyun.abel@...edance.com>
Cc: Peter Zijlstra <peterz@...radead.org>,
        Linux Kernel <linux-kernel@...r.kernel.org>, kvm@...r.kernel.org,
        virtualization@...ts.linux.dev, netdev@...r.kernel.org, mst@...hat.com,
        jasowang@...hat.com
Subject: Re: Re: EEVDF/vhost regression (bisected to 86bfbb7ce4f6 sched/fair:
 Add lag based placement)

On Fri, Nov 17, 2023 at 09:07:55PM +0800, Abel Wu wrote:
> On 11/17/23 8:37 PM, Peter Zijlstra Wrote:

[...]

> > Ah, so if this is a cgroup issue, it might be worth trying this patch
> > that we have in tip/sched/urgent.
> 
> And please also apply this fix:
> https://lore.kernel.org/all/20231117080106.12890-1-s921975628@gmail.com/
> 

We applied both suggested patch options and ran the test again, so 

sched/eevdf: Fix vruntime adjustment on reweight
sched/fair: Update min_vruntime for reweight_entity() correctly

and

sched/eevdf: Delay dequeue

Unfortunately, both variants do NOT fix the problem.
The regression remains unchanged.


I will continue getting myself familiar with how cgroups are scheduled to dig 
deeper here. If there are any other ideas, I'd be happy to use them as a 
starting point for further analysis.

Would additional traces still be of interest? If so, I would be glad to
provide them.

[...]