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From: Paolo Bonzini <pbonzini@redhat.com>
To: Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Steven Rostedt <rostedt@goodmis.org>,
	Sebastian Siewior <bigeasy@linutronix.de>,
	Anna-Maria Gleixner <anna-maria@linutronix.de>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Jiri Olsa <jolsa@redhat.com>, Juergen Gross <jgross@suse.com>
Subject: Re: [patch 07/12] KVM: LAPIC: Mark hrtimer to expire in hard interrupt context
Date: Fri, 26 Jul 2019 21:41:34 +0200
Message-ID: <6fea9141-1391-8466-0cf5-27f193daf5c9@redhat.com> (raw)
In-Reply-To: <20190726185753.363363474@linutronix.de>

On 26/07/19 20:30, Thomas Gleixner wrote:
> From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> 
> On PREEMPT_RT enabled kernels unmarked hrtimers are moved into soft
> interrupt expiry mode by default.
> 
> While that's not a functional requirement for the KVM local APIC timer
> emulation, it's a latency issue which can be avoided by marking the timer
> so hard interrupt context expiry is enforced.
> 
> No functional change.
> 
> [ tglx: Split out from larger combo patch. Add changelog. ]
> 
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: kvm@vger.kernel.org
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  arch/x86/kvm/lapic.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -2302,7 +2302,7 @@ int kvm_create_lapic(struct kvm_vcpu *vc
>  	apic->vcpu = vcpu;
>  
>  	hrtimer_init(&apic->lapic_timer.timer, CLOCK_MONOTONIC,
> -		     HRTIMER_MODE_ABS);
> +		     HRTIMER_MODE_ABS_HARD);
>  	apic->lapic_timer.timer.function = apic_timer_fn;
>  	if (timer_advance_ns == -1) {
>  		apic->lapic_timer.timer_advance_ns = LAPIC_TIMER_ADVANCE_ADJUST_INIT;
> 
> 

Acked-by: Paolo Bonzini <pbonzini@redhat.com>

  reply index

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-26 18:30 [patch 00/12] (hr)timers: Prepare for PREEMPT_RT support Thomas Gleixner
2019-07-26 18:30 ` [patch 01/12] hrtimer: Remove task argument from hrtimer_init_sleeper() Thomas Gleixner
2019-07-26 19:57   ` Steven Rostedt
2019-07-26 20:01     ` Thomas Gleixner
2019-07-30 22:07   ` [tip:timers/core] " tip-bot for Thomas Gleixner
2019-07-26 18:30 ` [patch 02/12] hrtimer: Consolidate hrtimer_init() + hrtimer_init_sleeper() calls Thomas Gleixner
2019-07-30 22:08   ` [tip:timers/core] " tip-bot for Sebastian Andrzej Siewior
2019-08-01 15:49   ` tip-bot for Sebastian Andrzej Siewior
2019-07-26 18:30 ` [patch 03/12] hrtimer: Introduce HARD expiry mode Thomas Gleixner
2019-07-30 22:10   ` [tip:timers/core] " tip-bot for Sebastian Andrzej Siewior
2019-08-01 15:52   ` tip-bot for Sebastian Andrzej Siewior
2019-07-26 18:30 ` [patch 04/12] sched: Mark hrtimers to expire in hard interrupt context Thomas Gleixner
2019-07-30 22:11   ` [tip:timers/core] " tip-bot for Thomas Gleixner
2019-08-01 15:53   ` tip-bot for Sebastian Andrzej Siewior
2019-08-01 18:58   ` tip-bot for Sebastian Andrzej Siewior
2019-07-26 18:30 ` [patch 05/12] perf/core: " Thomas Gleixner
2019-07-30 22:12   ` [tip:timers/core] " tip-bot for Thomas Gleixner
2019-08-01 15:54   ` tip-bot for Sebastian Andrzej Siewior
2019-08-01 18:59   ` tip-bot for Sebastian Andrzej Siewior
2019-07-26 18:30 ` [patch 06/12] watchdog: Mark watchdog_hrtimer " Thomas Gleixner
2019-07-30 22:13   ` [tip:timers/core] " tip-bot for Sebastian Andrzej Siewior
2019-08-01 15:55   ` tip-bot for Sebastian Andrzej Siewior
2019-08-01 19:00   ` tip-bot for Sebastian Andrzej Siewior
2019-07-26 18:30 ` [patch 07/12] KVM: LAPIC: Mark hrtimer " Thomas Gleixner
2019-07-26 19:41   ` Paolo Bonzini [this message]
2019-07-30 22:14   ` [tip:timers/core] " tip-bot for Sebastian Andrzej Siewior
2019-08-01 15:55   ` tip-bot for Sebastian Andrzej Siewior
2019-08-01 19:01   ` tip-bot for Sebastian Andrzej Siewior
2019-07-26 18:30 ` [patch 08/12] tick: Mark tick related hrtimers to expiry " Thomas Gleixner
2019-07-30 22:14   ` [tip:timers/core] " tip-bot for Sebastian Andrzej Siewior
2019-08-01 15:56   ` tip-bot for Sebastian Andrzej Siewior
2019-08-01 19:01   ` tip-bot for Sebastian Andrzej Siewior
2019-07-26 18:30 ` [patch 09/12] hrtimer: Move unmarked hrtimers to soft interrupt expiry on RT Thomas Gleixner
2019-07-30 22:15   ` [tip:timers/core] " tip-bot for Sebastian Andrzej Siewior
2019-08-01 15:57   ` tip-bot for Sebastian Andrzej Siewior
2019-08-01 19:02   ` tip-bot for Sebastian Andrzej Siewior
2019-07-26 18:30 ` [patch 10/12] hrtimer: Determine hard/soft expiry mode for hrtimer sleepers " Thomas Gleixner
2019-07-26 20:44   ` Steven Rostedt
2019-07-26 20:52     ` Thomas Gleixner
2019-07-26 20:56       ` Steven Rostedt
2019-07-26 21:16   ` Julia Cartwright
2019-07-26 21:30     ` Steven Rostedt
2019-07-26 21:35     ` Thomas Gleixner
2019-07-30 22:16   ` [tip:timers/core] " tip-bot for Sebastian Andrzej Siewior
2019-08-01 15:58   ` tip-bot for Sebastian Andrzej Siewior
2019-08-01 19:03   ` tip-bot for Sebastian Andrzej Siewior
2019-07-26 18:30 ` [patch 11/12] hrtimer: Prepare support for PREEMPT_RT Thomas Gleixner
2019-07-28  9:06   ` Juergen Gross
2019-07-29 15:08     ` Steven Rostedt
2019-07-29 17:30       ` Paolo Bonzini
2019-07-31  8:45         ` Juergen Gross
2019-07-30 22:17   ` [tip:timers/core] " tip-bot for Anna-Maria Gleixner
2019-08-01 15:58   ` tip-bot for Anna-Maria Gleixner
2019-08-01 19:04   ` tip-bot for Anna-Maria Gleixner
2019-08-20 13:26     ` Frederic Weisbecker
2019-08-23  2:12       ` [tip: timers/core] hrtimer: Improve comments on handling priority inversion against softirq kthread tip-bot2 for Frederic Weisbecker
2019-07-26 18:31 ` [patch 12/12] timers: Prepare support for PREEMPT_RT Thomas Gleixner
2019-07-30 22:17   ` [tip:timers/core] " tip-bot for Anna-Maria Gleixner
2019-08-01 15:59   ` tip-bot for Anna-Maria Gleixner
2019-08-01 19:04   ` tip-bot for Anna-Maria Gleixner
2019-07-29 19:45 ` [patch 00/12] (hr)timers: Prepare for PREEMPT_RT support Peter Zijlstra

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