From: Sudeep Holla <sudeep.holla@arm.com>
To: Hsin-Yi Wang <hsinyi@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Jiri Kosina <jkosina@suse.cz>,
Pavankumar Kondeti <pkondeti@codeaurora.org>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Aaro Koskinen <aaro.koskinen@nokia.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Will Deacon <will@kernel.org>, Fenghua Yu <fenghua.yu@intel.com>,
James Morse <james.morse@arm.com>,
Mark Rutland <mark.rutland@arm.com>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Guenter Roeck <groeck@chromium.org>,
Stephen Boyd <swboyd@chromium.org>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org,
linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org,
linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org,
Sudeep Holla <sudeep.holla@arm.com>,
linux-pm@vger.kernel.org
Subject: Re: [PATCH v5] reboot: support offline CPUs before reboot
Date: Wed, 15 Jan 2020 11:41:12 +0000 [thread overview]
Message-ID: <20200115114112.GA3663@bogus> (raw)
In-Reply-To: <20200115063410.131692-1-hsinyi@chromium.org>
On Wed, Jan 15, 2020 at 02:34:10PM +0800, Hsin-Yi Wang wrote:
> Currently system reboots uses architecture specific codes (smp_send_stop)
> to offline non reboot CPUs. Most architecture's implementation is looping
> through all non reboot online CPUs and call ipi function to each of them. Some
> architecture like arm64, arm, and x86... would set offline masks to cpu without
> really offline them. This causes some race condition and kernel warning comes
> out sometimes when system reboots.
>
> This patch adds a config ARCH_OFFLINE_CPUS_ON_REBOOT, which would offline cpus in
> migrate_to_reboot_cpu(). If non reboot cpus are all offlined here, the loop for
> checking online cpus would be an empty loop. If architecture don't enable this
> config, or some cpus somehow fails to offline, it would fallback to ipi
> function.
>
What's the timing impact on systems with large number of CPUs(say 256 or
more) ? I remember we added some change to reduce the wait times for
offlining CPUs in system suspend path on arm64, still not negligible.
--
Regards,
Sudeep
WARNING: multiple messages have this Message-ID (diff)
From: Sudeep Holla <sudeep.holla@arm.com>
To: Hsin-Yi Wang <hsinyi@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org,
Guenter Roeck <groeck@chromium.org>,
Will Deacon <will@kernel.org>, Ingo Molnar <mingo@kernel.org>,
linux-s390@vger.kernel.org, linux-csky@vger.kernel.org,
Aaro Koskinen <aaro.koskinen@nokia.com>,
Fenghua Yu <fenghua.yu@intel.com>,
linux-pm@vger.kernel.org, linux-xtensa@linux-xtensa.org,
Sudeep Holla <sudeep.holla@arm.com>,
Stephen Boyd <swboyd@chromium.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Pavankumar Kondeti <pkondeti@codeaurora.org>,
linux-arm-kernel@lists.infradead.org,
linux-parisc@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-mips@vger.kernel.org, James Morse <james.morse@arm.com>,
Jiri Kosina <jkosina@suse.cz>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v5] reboot: support offline CPUs before reboot
Date: Wed, 15 Jan 2020 11:41:12 +0000 [thread overview]
Message-ID: <20200115114112.GA3663@bogus> (raw)
In-Reply-To: <20200115063410.131692-1-hsinyi@chromium.org>
On Wed, Jan 15, 2020 at 02:34:10PM +0800, Hsin-Yi Wang wrote:
> Currently system reboots uses architecture specific codes (smp_send_stop)
> to offline non reboot CPUs. Most architecture's implementation is looping
> through all non reboot online CPUs and call ipi function to each of them. Some
> architecture like arm64, arm, and x86... would set offline masks to cpu without
> really offline them. This causes some race condition and kernel warning comes
> out sometimes when system reboots.
>
> This patch adds a config ARCH_OFFLINE_CPUS_ON_REBOOT, which would offline cpus in
> migrate_to_reboot_cpu(). If non reboot cpus are all offlined here, the loop for
> checking online cpus would be an empty loop. If architecture don't enable this
> config, or some cpus somehow fails to offline, it would fallback to ipi
> function.
>
What's the timing impact on systems with large number of CPUs(say 256 or
more) ? I remember we added some change to reduce the wait times for
offlining CPUs in system suspend path on arm64, still not negligible.
--
Regards,
Sudeep
WARNING: multiple messages have this Message-ID (diff)
From: Sudeep Holla <sudeep.holla@arm.com>
To: Hsin-Yi Wang <hsinyi@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>,
linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org,
Guenter Roeck <groeck@chromium.org>,
Will Deacon <will@kernel.org>, Ingo Molnar <mingo@kernel.org>,
linux-s390@vger.kernel.org, linux-csky@vger.kernel.org,
Aaro Koskinen <aaro.koskinen@nokia.com>,
Fenghua Yu <fenghua.yu@intel.com>,
linux-pm@vger.kernel.org, linux-xtensa@linux-xtensa.org,
Sudeep Holla <sudeep.holla@arm.com>,
Stephen Boyd <swboyd@chromium.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Pavankumar Kondeti <pkondeti@codeaurora.org>,
linux-arm-kernel@lists.infradead.org,
linux-parisc@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-mips@vger.kernel.org, James Morse <james.morse@arm.com>,
Jiri Kosina <jkosina@suse.cz>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v5] reboot: support offline CPUs before reboot
Date: Wed, 15 Jan 2020 11:41:12 +0000 [thread overview]
Message-ID: <20200115114112.GA3663@bogus> (raw)
In-Reply-To: <20200115063410.131692-1-hsinyi@chromium.org>
On Wed, Jan 15, 2020 at 02:34:10PM +0800, Hsin-Yi Wang wrote:
> Currently system reboots uses architecture specific codes (smp_send_stop)
> to offline non reboot CPUs. Most architecture's implementation is looping
> through all non reboot online CPUs and call ipi function to each of them. Some
> architecture like arm64, arm, and x86... would set offline masks to cpu without
> really offline them. This causes some race condition and kernel warning comes
> out sometimes when system reboots.
>
> This patch adds a config ARCH_OFFLINE_CPUS_ON_REBOOT, which would offline cpus in
> migrate_to_reboot_cpu(). If non reboot cpus are all offlined here, the loop for
> checking online cpus would be an empty loop. If architecture don't enable this
> config, or some cpus somehow fails to offline, it would fallback to ipi
> function.
>
What's the timing impact on systems with large number of CPUs(say 256 or
more) ? I remember we added some change to reduce the wait times for
offlining CPUs in system suspend path on arm64, still not negligible.
--
Regards,
Sudeep
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-01-15 11:41 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-15 6:34 [PATCH v5] reboot: support offline CPUs before reboot Hsin-Yi Wang
2020-01-15 6:34 ` Hsin-Yi Wang
2020-01-15 6:34 ` Hsin-Yi Wang
2020-01-15 6:34 ` Hsin-Yi Wang
2020-01-15 9:49 ` Rafael J. Wysocki
2020-01-15 9:49 ` Rafael J. Wysocki
2020-01-15 9:49 ` Rafael J. Wysocki
2020-01-15 9:49 ` Rafael J. Wysocki
2020-01-15 11:34 ` Hsin-Yi Wang
2020-01-15 11:34 ` Hsin-Yi Wang
2020-01-15 11:34 ` Hsin-Yi Wang
2020-01-15 11:34 ` Hsin-Yi Wang
2020-01-15 11:41 ` Sudeep Holla [this message]
2020-01-15 11:41 ` Sudeep Holla
2020-01-15 11:41 ` Sudeep Holla
2020-01-16 9:25 ` Hsin-Yi Wang
2020-01-16 9:25 ` Hsin-Yi Wang
2020-01-16 9:25 ` Hsin-Yi Wang
2020-01-16 9:25 ` Hsin-Yi Wang
2020-01-16 0:30 ` Thomas Gleixner
2020-01-16 0:30 ` Thomas Gleixner
2020-01-16 0:30 ` Thomas Gleixner
2020-01-16 0:30 ` Thomas Gleixner
2020-01-16 9:18 ` Hsin-Yi Wang
2020-01-16 9:18 ` Hsin-Yi Wang
2020-01-16 9:18 ` Hsin-Yi Wang
2020-01-16 9:18 ` Hsin-Yi Wang
2020-01-16 11:10 ` Thomas Gleixner
2020-01-16 11:10 ` Thomas Gleixner
2020-01-16 11:10 ` Thomas Gleixner
2020-01-16 11:10 ` Thomas Gleixner
2020-01-16 11:10 ` Thomas Gleixner
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