From: Juergen Gross <jgross@suse.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Steven Rostedt <rostedt@goodmis.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
x86@kernel.org, Anna-Maria Gleixner <anna-maria@linutronix.de>,
Sebastian Siewior <bigeasy@linutronix.de>,
Thomas Gleixner <tglx@linutronix.de>,
Jiri Olsa <jolsa@redhat.com>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [patch 11/12] hrtimer: Prepare support for PREEMPT_RT
Date: Wed, 31 Jul 2019 10:45:56 +0200 [thread overview]
Message-ID: <0910bd2b-b5b1-aa41-7f5e-b44f51a516d3@suse.com> (raw)
In-Reply-To: <9a9bde89-e0b3-a7b9-749e-a6b35d74b729@redhat.com>
On 29.07.19 19:30, Paolo Bonzini wrote:
> On 29/07/19 17:08, Steven Rostedt wrote:
>> On Sun, 28 Jul 2019 11:06:50 +0200
>> Juergen Gross <jgross@suse.com> wrote:
>>
>>> In case we'd want to change that I'd rather not special case timers, but
>>> apply a more general solution to the quite large amount of similar
>>> cases: I assume the majority of cpu_relax() uses are affected, so adding
>>> a paravirt op cpu_relax() might be appropriate.
>>>
>>> That could be put under CONFIG_PARAVIRT_SPINLOCK. If called in a guest
>>> it could ask the hypervisor to give up the physical cpu voluntarily
>>> (in Xen this would be a "yield" hypercall).
>>
>> Seems paravirt wants our cpu_chill() ;-)
>
> Actually that is not really a joke! :)
As CONFIG_PARAVIRT is no longer so massive intrusive as some time ago
it might really be worth thinking of.
From Xen perspective I'd really like a way to give up the vcpu instead
of doing a busy wait. And having another user and (even better) already
some patches addressing some (or all?) callsites sounds like a win-win
situation for me.
So +1 from me for cpu_chill() via a new paravirt op.
Juergen
next prev parent reply other threads:[~2019-07-31 8:46 UTC|newest]
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
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 [this message]
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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