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From: Peter Zijlstra <peterz@infradead.org>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Ingo Molnar <mingo@redhat.com>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
	linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v2 3/5] kernel/cpu: Allow non-zero CPU to be primary for suspend / kexec freeze
Date: Thu, 25 Apr 2019 14:02:21 +0200	[thread overview]
Message-ID: <20190425120221.GR4038@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190411033448.20842-4-npiggin@gmail.com>

On Thu, Apr 11, 2019 at 01:34:46PM +1000, Nicholas Piggin wrote:
> This patch provides an arch option, ARCH_SUSPEND_NONZERO_CPU, to
> opt-in to allowing suspend to occur on one of the housekeeping CPUs
> rather than hardcoded CPU0.
> 
> This will allow CPU0 to be a nohz_full CPU with a later change.
> 
> It may be possible for platforms with hardware/firmware restrictions
> on suspend/wake effectively support this by handing off the final
> stage to CPU0 when kernel housekeeping is no longer required. Another
> option is to make housekeeping / nohz_full mask dynamic at runtime,
> but the complexity could not be justified at this time.

Should we not tie this into whatever already allows an achitecture to
hotplug CPU-0? For instance, x86 default disallows this but has
cpu0_hotpluggable to allow this.

Presumably POWER already allows hotplugging CPU-0 ?



WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: linux-arch@vger.kernel.org,
	Frederic Weisbecker <fweisbec@gmail.com>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
	linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v2 3/5] kernel/cpu: Allow non-zero CPU to be primary for suspend / kexec freeze
Date: Thu, 25 Apr 2019 14:02:21 +0200	[thread overview]
Message-ID: <20190425120221.GR4038@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190411033448.20842-4-npiggin@gmail.com>

On Thu, Apr 11, 2019 at 01:34:46PM +1000, Nicholas Piggin wrote:
> This patch provides an arch option, ARCH_SUSPEND_NONZERO_CPU, to
> opt-in to allowing suspend to occur on one of the housekeeping CPUs
> rather than hardcoded CPU0.
> 
> This will allow CPU0 to be a nohz_full CPU with a later change.
> 
> It may be possible for platforms with hardware/firmware restrictions
> on suspend/wake effectively support this by handing off the final
> stage to CPU0 when kernel housekeeping is no longer required. Another
> option is to make housekeeping / nohz_full mask dynamic at runtime,
> but the complexity could not be justified at this time.

Should we not tie this into whatever already allows an achitecture to
hotplug CPU-0? For instance, x86 default disallows this but has
cpu0_hotpluggable to allow this.

Presumably POWER already allows hotplugging CPU-0 ?



  reply	other threads:[~2019-04-25 12:02 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-11  3:34 [PATCH v2 0/5] Allow CPU0 to be nohz full Nicholas Piggin
2019-04-11  3:34 ` Nicholas Piggin
2019-04-11  3:34 ` [PATCH v2 1/5] sched/core: allow the remote scheduler tick to be started on CPU0 Nicholas Piggin
2019-04-11  3:34   ` Nicholas Piggin
2019-05-03 11:28   ` [tip:sched/core] sched/core: Allow " tip-bot for Nicholas Piggin
2019-04-11  3:34 ` [PATCH v2 2/5] PM / suspend: add function to disable secondaries for suspend Nicholas Piggin
2019-04-11  3:34   ` Nicholas Piggin
2019-05-03 11:29   ` [tip:sched/core] power/suspend: Add " tip-bot for Nicholas Piggin
2019-05-03 17:46   ` tip-bot for Nicholas Piggin
2019-04-11  3:34 ` [PATCH v2 3/5] kernel/cpu: Allow non-zero CPU to be primary for suspend / kexec freeze Nicholas Piggin
2019-04-11  3:34   ` Nicholas Piggin
2019-04-25 12:02   ` Peter Zijlstra [this message]
2019-04-25 12:02     ` Peter Zijlstra
2019-04-26  4:32     ` Nicholas Piggin
2019-04-26  4:32       ` Nicholas Piggin
2019-05-03 11:29   ` [tip:sched/core] " tip-bot for Nicholas Piggin
2019-05-03 17:46   ` tip-bot for Nicholas Piggin
2019-04-11  3:34 ` [PATCH v2 4/5] kernel/sched/isolation: require a present CPU in housekeeping mask Nicholas Piggin
2019-04-11  3:34   ` Nicholas Piggin
2019-05-03 11:30   ` [tip:sched/core] sched/isolation: Require " tip-bot for Nicholas Piggin
2019-05-03 17:47   ` tip-bot for Nicholas Piggin
2019-05-03 23:52     ` Frederic Weisbecker
2019-05-04  0:27     ` Frederic Weisbecker
2019-05-04  6:59       ` Nicholas Piggin
2019-05-06 15:16         ` Frederic Weisbecker
2019-05-06 23:50           ` Nicholas Piggin
2019-05-08  0:35             ` Frederic Weisbecker
2019-05-08  1:38               ` Nicholas Piggin
2019-04-11  3:34 ` [PATCH v2 5/5] nohz_full: Allow the boot CPU to be nohz_full Nicholas Piggin
2019-04-11  3:34   ` Nicholas Piggin
2019-05-03 11:31   ` [tip:sched/core] " tip-bot for Nicholas Piggin
2019-05-03 17:48   ` tip-bot for Nicholas Piggin
2019-04-25 12:04 ` [PATCH v2 0/5] Allow CPU0 to be nohz full Peter Zijlstra
2019-04-25 12:04   ` Peter Zijlstra
2019-04-30  2:46   ` Nicholas Piggin
2019-04-30  2:46     ` Nicholas Piggin
2019-04-30 12:07     ` Peter Zijlstra
2019-04-30 12:07       ` Peter Zijlstra

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