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From: Waiman Long <longman@redhat.com>
To: Arnd Bergmann <arnd@kernel.org>
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 14:25:32 -0400	[thread overview]
Message-ID: <d7af2422-3264-b9bb-b515-da4351743448@redhat.com> (raw)
In-Reply-To: <CAK8P3a3JEBF-dEg0iVThMMRNK3CDxY+mRtTeStMusycnethO_g@mail.gmail.com>

On 10/25/21 11:44 AM, Arnd Bergmann wrote:
> 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.

Yes, you are right. Their queued lock code looks like a custom version 
of the pvqspinlock code.

Cheers,
Longman


      reply	other threads:[~2021-10-25 18:25 UTC|newest]

Thread overview: 12+ 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 14:10 ` Helge Deller
2021-10-23  1:37 ` Waiman Long
2021-10-23 16:04   ` Arnd Bergmann
2021-10-25  9:57     ` Peter Zijlstra
2021-10-25 10:06       ` Peter Zijlstra
2021-10-25 13:06       ` Arnd Bergmann
2021-10-25 14:33         ` Peter Zijlstra
2021-10-27 12:01           ` Michael Ellerman
2021-10-25 15:28         ` Waiman Long
2021-10-25 15:44           ` Arnd Bergmann
2021-10-25 18:25             ` Waiman Long [this message]

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