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

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Date:   Tue, 31 Jan 2023 11:02:27 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Josh Poimboeuf <jpoimboe@...nel.org>
Cc:     Petr Mladek <pmladek@...e.com>,
        Joe Lawrence <joe.lawrence@...hat.com>, kvm@...r.kernel.org,
        "Michael S. Tsirkin" <mst@...hat.com>, netdev@...r.kernel.org,
        Jiri Kosina <jikos@...nel.org>, linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        "Seth Forshee (DigitalOcean)" <sforshee@...italocean.com>,
        live-patching@...r.kernel.org, Miroslav Benes <mbenes@...e.cz>
Subject: Re: [PATCH 0/2] vhost: improve livepatch switching for heavily
 loaded vhost worker kthreads

On Mon, Jan 30, 2023 at 11:59:30AM -0800, Josh Poimboeuf wrote:

> @@ -8662,16 +8665,19 @@ void sched_dynamic_update(int mode)
>  
>  	switch (mode) {
>  	case preempt_dynamic_none:
> -		preempt_dynamic_enable(cond_resched);
> +		if (!klp_override)
> +			preempt_dynamic_enable(cond_resched);
>  		preempt_dynamic_disable(might_resched);
>  		preempt_dynamic_disable(preempt_schedule);
>  		preempt_dynamic_disable(preempt_schedule_notrace);
>  		preempt_dynamic_disable(irqentry_exit_cond_resched);
> +		//FIXME avoid printk for klp restore

		if (mode != preempt_dynamic_mode)

>  		pr_info("Dynamic Preempt: none\n");
>  		break;
>  
>  	case preempt_dynamic_voluntary:
> -		preempt_dynamic_enable(cond_resched);
> +		if (!klp_override)
> +			preempt_dynamic_enable(cond_resched);
>  		preempt_dynamic_enable(might_resched);
>  		preempt_dynamic_disable(preempt_schedule);
>  		preempt_dynamic_disable(preempt_schedule_notrace);