On Tue, Mar 12, 2024 at 09:45:57AM +0000, Luis Machado wrote: > On 3/11/24 17:05, Michael S. Tsirkin wrote: > > > > Are we going anywhere with this btw? > > > > > > I think Tobias had a couple other threads related to this, with other potential fixes: > > https://lore.kernel.org/lkml/20240228161018.14253-1-huschle@xxxxxxxxxxxxx/ > > https://lore.kernel.org/lkml/20240228161023.14310-1-huschle@xxxxxxxxxxxxx/ > Sorry, Michael, should have provided those threads here as well. The more I look into this issue, the more things to ponder upon I find. It seems like this issue can (maybe) be fixed on the scheduler side after all. The root cause of this regression remains that the mentioned kworker gets a negative lag value and is therefore not elligible to run on wake up. This negative lag is potentially assigned incorrectly. But I'm not sure yet. Anytime I find something that can address the symptom, there is a potential root cause on another level, and I would like to avoid to just address a symptom to fix the issue, wheras it would be better to find the actual root cause. I would nevertheless still argue, that vhost relies rather heavily on the fact that the kworker gets scheduled on wake up everytime. But I don't have a proposal at hand that accounts for potential side effects if opting for explicitly initiating a schedule. Maybe the assumption, that said kworker should always be selected on wake up is valid. In that case the explicit schedule would merely be a safety net. I will let you know if something comes up on the scheduler side. There are some more ideas on my side how this could be approached.
