Re: [PATCH 0/6] sched/proxy: doodles..

[Peter Zijlstra <peterz@infradead.org>]

I managed to screw up the emails and most MTAs refused to accept. Mails
made their to lore though.

On Tue, May 26, 2026 at 01:16:09PM +0200, Peter Zijlstra wrote:
> This goes on top of queue:sched/proxy.
> 
> I was trying to do some cleanups and playing around with that PROXY_WAKING
> removal, and also moving towards using ->is_blocked to replace the core
> se.sched_delayed usage.
> 
> But aside from making a few silly mistakes and taking far too long to figure
> out WTF happened, I've ran into a snag with the scheme to remove PROXY_WAKING.
> 
> This happens in patch #4, where we switch the proxy paths to be guarded by
> ->is_blocked, rather than ->blocked_on. This works fine for schedule() /
> pick_next_task, since that guarantees there are no delayed tasks.
> 
> However ttwu_runnable() has no such luck, and if ->is_blocked is all we have,
> then it turns out that we'll always fully block delayed tasks and send then
> through the long path.
> 
> Now, I did me some ttwu-delayed patches a while ago, and Mike has been poking
> me about them. Those patches pick out the delayed things before we take locks,
> so perhaps we can resolve this that way. I'll have to poke a bit more.
> 
> In the meantime, I figured I'd share the patches I got... I think at least the
> first 3 might live :-)

https://lore.kernel.org/all/20260526111609.433880331@infradead.org/T/#u