Re: [PATCH 0/2] vhost: improve livepatch switching for heavily loaded vhost worker kthreads

[Josh Poimboeuf]

On Fri, Jan 27, 2023 at 08:52:38AM -0800, Josh Poimboeuf wrote:
> On Fri, Jan 27, 2023 at 11:37:02AM +0100, Peter Zijlstra wrote:
> > On Thu, Jan 26, 2023 at 08:43:55PM -0800, Josh Poimboeuf wrote:
> > > Here's another idea, have we considered this?  Have livepatch set
> > > TIF_NEED_RESCHED on all kthreads to force them into schedule(), and then
> > > have the scheduler call klp_try_switch_task() if TIF_PATCH_PENDING is
> > > set.
> > > 
> > > Not sure how scheduler folks would feel about that ;-)
> 
> Hmmmm, with preemption I guess the above doesn't work for kthreads
> calling cond_resched() instead of what vhost_worker() does (explicit
> need_resched/schedule).

Though I guess we could hook into cond_resched() too if we make it a
non-NOP for PREEMPT+LIVEPATCH?

-- 
Josh