Re: [PATCH] sched/fair: fix pick_eevdf to always find the correct se

[Mike Galbraith]

On Fri, 2023-10-06 at 16:00 +0200, Peter Zijlstra wrote:
> On Fri, Oct 06, 2023 at 12:31:28PM +0200, Mike Galbraith wrote:
> > On Fri, 2023-10-06 at 10:35 +0200, Marek Szyprowski wrote:
> > >
> > >
> > > Just to note, I've run into this issue on the QEmu's 'arm64/virt'
> > > platform, not on the Samsung specific hardware. 
> >
> > It doesn't appear to be arch specific, all I have to do is enable
> > autogroup, raspberry or x86_64 desktop box, the occasional failure
> > tripping over task groups, leaving both best and best_left with
> > identical but not what we're looking for ->min_deadline.
>
> OK, autogroups enabled and booted, /debug/sched/debug shows autogroups
> are indeed in existence.
>
> I've ran hackbench and a kernel build, but no whoopsie yet :-(
>
> I suppose I'll kick some benchmarks and go make a cup 'o tea or
> something.

Hm, just booting gets me a handful, and generic desktop activity
produces a fairly regular supply.  This is virgin 6.6.0.ga9e6eb3-tip.

[  340.473123] EEVDF scheduling fail, picking leftmost
[  340.473132] EEVDF scheduling fail, picking leftmost
[  343.656549] EEVDF scheduling fail, picking leftmost
[  343.656557] EEVDF scheduling fail, picking leftmost
[  343.690463] EEVDF scheduling fail, picking leftmost
[  343.690472] EEVDF scheduling fail, picking leftmost
[  426.224039] EEVDF scheduling fail, picking leftmost
[  426.224080] EEVDF scheduling fail, picking leftmost
[  426.224084] EEVDF scheduling fail, picking leftmost
[  426.363323] EEVDF scheduling fail, picking leftmost
[  426.759244] EEVDF scheduling fail, picking leftmost
[  426.759256] EEVDF scheduling fail, picking leftmost
[  441.872524] EEVDF scheduling fail, picking leftmost
[  441.872556] EEVDF scheduling fail, picking leftmost