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From: Arnd Bergmann <arnd@kernel.org>
To: Waiman Long <longman@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
	Arnd Bergmann <arnd@arndb.de>, Boqun Feng <boqun.feng@gmail.com>,
	Jonas Bonn <jonas@southpole.se>,
	Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
	Stafford Horne <shorne@gmail.com>,
	"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
	Helge Deller <deller@gmx.de>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Heiko Carstens <hca@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Alexander Gordeev <agordeev@linux.ibm.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-ia64@vger.kernel.org,
	Openrisc <openrisc@lists.librecores.org>,
	Parisc List <linux-parisc@vger.kernel.org>,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
	linux-s390 <linux-s390@vger.kernel.org>
Subject: Re: [PATCH] locking: remove spin_lock_flags() etc
Date: Mon, 25 Oct 2021 17:44:26 +0200	[thread overview]
Message-ID: <CAK8P3a3JEBF-dEg0iVThMMRNK3CDxY+mRtTeStMusycnethO_g@mail.gmail.com> (raw)
In-Reply-To: <2413f412-a390-bbc0-e848-e2a77d1f0ab3@redhat.com>

On Mon, Oct 25, 2021 at 5:28 PM Waiman Long <longman@redhat.com> wrote:
> On 10/25/21 9:06 AM, Arnd Bergmann wrote:
> >
> > On s390, we pick between the cmpxchg() based directed-yield when
> > running on virtualized CPUs, and a normal qspinlock when running on a
> > dedicated CPU.
>
> I am not aware that s390 is using qspinlocks at all as I don't see
> ARCH_USE_QUEUED_SPINLOCKS being set anywhere under arch/s390. I only see
> that it uses a cmpxchg based spinlock.

Sorry, I should not have said "normal" here. See arch/s390/lib/spinlock.c
for their custom queued spinlocks as implemented in arch_spin_lock_queued().
I don't know if that code actually does the same thing as the generic qspinlock,
but it seems at least similar.

       Arnd

WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd@kernel.org>
To: Waiman Long <longman@redhat.com>
Cc: linux-ia64@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
	"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
	Paul Mackerras <paulus@samba.org>,
	Alexander Gordeev <agordeev@linux.ibm.com>,
	Will Deacon <will@kernel.org>, Jonas Bonn <jonas@southpole.se>,
	linux-s390 <linux-s390@vger.kernel.org>,
	Arnd Bergmann <arnd@arndb.de>, Helge Deller <deller@gmx.de>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Ingo Molnar <mingo@redhat.com>,
	Heiko Carstens <hca@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Boqun Feng <boqun.feng@gmail.com>,
	Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
	Openrisc <openrisc@lists.librecores.org>,
	Stafford Horne <shorne@gmail.com>,
	Parisc List <linux-parisc@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH] locking: remove spin_lock_flags() etc
Date: Mon, 25 Oct 2021 17:44:26 +0200	[thread overview]
Message-ID: <CAK8P3a3JEBF-dEg0iVThMMRNK3CDxY+mRtTeStMusycnethO_g@mail.gmail.com> (raw)
In-Reply-To: <2413f412-a390-bbc0-e848-e2a77d1f0ab3@redhat.com>

On Mon, Oct 25, 2021 at 5:28 PM Waiman Long <longman@redhat.com> wrote:
> On 10/25/21 9:06 AM, Arnd Bergmann wrote:
> >
> > On s390, we pick between the cmpxchg() based directed-yield when
> > running on virtualized CPUs, and a normal qspinlock when running on a
> > dedicated CPU.
>
> I am not aware that s390 is using qspinlocks at all as I don't see
> ARCH_USE_QUEUED_SPINLOCKS being set anywhere under arch/s390. I only see
> that it uses a cmpxchg based spinlock.

Sorry, I should not have said "normal" here. See arch/s390/lib/spinlock.c
for their custom queued spinlocks as implemented in arch_spin_lock_queued().
I don't know if that code actually does the same thing as the generic qspinlock,
but it seems at least similar.

       Arnd

WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd@kernel.org>
To: openrisc@lists.librecores.org
Subject: [OpenRISC] [PATCH] locking: remove spin_lock_flags() etc
Date: Mon, 25 Oct 2021 17:44:26 +0200	[thread overview]
Message-ID: <CAK8P3a3JEBF-dEg0iVThMMRNK3CDxY+mRtTeStMusycnethO_g@mail.gmail.com> (raw)
In-Reply-To: <2413f412-a390-bbc0-e848-e2a77d1f0ab3@redhat.com>

On Mon, Oct 25, 2021 at 5:28 PM Waiman Long <longman@redhat.com> wrote:
> On 10/25/21 9:06 AM, Arnd Bergmann wrote:
> >
> > On s390, we pick between the cmpxchg() based directed-yield when
> > running on virtualized CPUs, and a normal qspinlock when running on a
> > dedicated CPU.
>
> I am not aware that s390 is using qspinlocks at all as I don't see
> ARCH_USE_QUEUED_SPINLOCKS being set anywhere under arch/s390. I only see
> that it uses a cmpxchg based spinlock.

Sorry, I should not have said "normal" here. See arch/s390/lib/spinlock.c
for their custom queued spinlocks as implemented in arch_spin_lock_queued().
I don't know if that code actually does the same thing as the generic qspinlock,
but it seems at least similar.

       Arnd

WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd@kernel.org>
To: Waiman Long <longman@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
	Arnd Bergmann <arnd@arndb.de>, Boqun Feng <boqun.feng@gmail.com>,
	Jonas Bonn <jonas@southpole.se>,
	Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
	Stafford Horne <shorne@gmail.com>,
	"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
	Helge Deller <deller@gmx.de>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Heiko Carstens <hca@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Alexander Gordeev <agordeev@linux.ibm.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-ia64@vger.kernel.org,
	Openrisc <openrisc@lists.librecores.org>,
	Parisc List <linux-parisc@vger.kernel.org>,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
	linux-s390 <linux-s390@vger.kernel.org>
Subject: Re: [PATCH] locking: remove spin_lock_flags() etc
Date: Mon, 25 Oct 2021 15:44:26 +0000	[thread overview]
Message-ID: <CAK8P3a3JEBF-dEg0iVThMMRNK3CDxY+mRtTeStMusycnethO_g@mail.gmail.com> (raw)
In-Reply-To: <2413f412-a390-bbc0-e848-e2a77d1f0ab3@redhat.com>

On Mon, Oct 25, 2021 at 5:28 PM Waiman Long <longman@redhat.com> wrote:
> On 10/25/21 9:06 AM, Arnd Bergmann wrote:
> >
> > On s390, we pick between the cmpxchg() based directed-yield when
> > running on virtualized CPUs, and a normal qspinlock when running on a
> > dedicated CPU.
>
> I am not aware that s390 is using qspinlocks at all as I don't see
> ARCH_USE_QUEUED_SPINLOCKS being set anywhere under arch/s390. I only see
> that it uses a cmpxchg based spinlock.

Sorry, I should not have said "normal" here. See arch/s390/lib/spinlock.c
for their custom queued spinlocks as implemented in arch_spin_lock_queued().
I don't know if that code actually does the same thing as the generic qspinlock,
but it seems at least similar.

       Arnd

  reply	other threads:[~2021-10-25 15:44 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-22 11:59 [PATCH] locking: remove spin_lock_flags() etc Arnd Bergmann
2021-10-22 11:59 ` Arnd Bergmann
2021-10-22 11:59 ` [OpenRISC] " Arnd Bergmann
2021-10-22 11:59 ` Arnd Bergmann
2021-10-22 14:10 ` Helge Deller
2021-10-22 14:10   ` Helge Deller
2021-10-22 14:10   ` [OpenRISC] " Helge Deller
2021-10-22 14:10   ` Helge Deller
2021-10-23  1:37 ` Waiman Long
2021-10-23  1:37   ` Waiman Long
2021-10-23  1:37   ` [OpenRISC] " Waiman Long
2021-10-23  1:37   ` Waiman Long
2021-10-23 16:04   ` Arnd Bergmann
2021-10-23 16:04     ` Arnd Bergmann
2021-10-23 16:04     ` [OpenRISC] " Arnd Bergmann
2021-10-23 16:04     ` Arnd Bergmann
2021-10-25  9:57     ` Peter Zijlstra
2021-10-25  9:57       ` Peter Zijlstra
2021-10-25  9:57       ` [OpenRISC] " Peter Zijlstra
2021-10-25  9:57       ` Peter Zijlstra
2021-10-25 10:06       ` Peter Zijlstra
2021-10-25 10:06         ` Peter Zijlstra
2021-10-25 10:06         ` [OpenRISC] " Peter Zijlstra
2021-10-25 10:06         ` Peter Zijlstra
2021-10-25 13:06       ` Arnd Bergmann
2021-10-25 13:06         ` Arnd Bergmann
2021-10-25 13:06         ` [OpenRISC] " Arnd Bergmann
2021-10-25 13:06         ` Arnd Bergmann
2021-10-25 14:33         ` Peter Zijlstra
2021-10-25 14:33           ` Peter Zijlstra
2021-10-25 14:33           ` [OpenRISC] " Peter Zijlstra
2021-10-25 14:33           ` Peter Zijlstra
2021-10-27 12:01           ` Michael Ellerman
2021-10-27 12:01             ` Michael Ellerman
2021-10-27 12:01             ` [OpenRISC] " Michael Ellerman
2021-10-27 12:01             ` Michael Ellerman
2021-10-25 15:28         ` Waiman Long
2021-10-25 15:28           ` Waiman Long
2021-10-25 15:28           ` [OpenRISC] " Waiman Long
2021-10-25 15:28           ` Waiman Long
2021-10-25 15:44           ` Arnd Bergmann [this message]
2021-10-25 15:44             ` Arnd Bergmann
2021-10-25 15:44             ` [OpenRISC] " Arnd Bergmann
2021-10-25 15:44             ` Arnd Bergmann
2021-10-25 18:25             ` Waiman Long
2021-10-25 18:25               ` Waiman Long
2021-10-25 18:25               ` [OpenRISC] " Waiman Long
2021-10-25 18:25               ` Waiman Long
2021-10-30 14:47 ` [tip: locking/core] locking: Remove " tip-bot2 for Arnd Bergmann

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