From: Arnd Bergmann <arnd@arndb.de>
To: Guo Ren <guoren@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>, Waiman Long <longman@redhat.com>,
Palmer Dabbelt <palmer@rivosinc.com>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
Boqun Feng <boqun.feng@gmail.com>,
linux-riscv <linux-riscv@lists.infradead.org>,
linux-arch <linux-arch@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Guo Ren <guoren@linux.alibaba.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH V7 4/5] asm-generic: spinlock: Add combo spinlock (ticket & queued)
Date: Wed, 29 Jun 2022 10:29:37 +0200 [thread overview]
Message-ID: <CAK8P3a3GiMgEJdBg5QQHHD0bDnpR0XwPkAw7=zT7ETzf6-sCmg@mail.gmail.com> (raw)
In-Reply-To: <CAJF2gTTtKiMZJLWBEcRz-4CmNojH0cOgpUYGupLyCXXFjQD_FQ@mail.gmail.com>
On Wed, Jun 29, 2022 at 10:24 AM Guo Ren <guoren@kernel.org> wrote:
> On Wed, Jun 29, 2022 at 3:09 PM Arnd Bergmann <arnd@arndb.de> wrote:
> > On Wed, Jun 29, 2022 at 3:34 AM Waiman Long <longman@redhat.com> wrote:
> >
> > From looking at the header file dependencies on arm64, I know that
> > putting jump labels into core infrastructure like the arch_spin_lock()
> > makes a big mess of indirect includes and measurably slows down
> > the kernel build.
> arm64 needn't combo spinlock, it could use pure qspinlock with keeping
> current header files included.
arm64 has a different problem: there are two separate sets of atomic
instructions, and the decision between those is similarly done using
jump labels. I definitely like the ability to choose between qspinlock
and ticket spinlock on arm64 as well. This can be done as a
compile-time choice, but both of them still depend on jump labels.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd@arndb.de>
To: Guo Ren <guoren@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>, Waiman Long <longman@redhat.com>,
Palmer Dabbelt <palmer@rivosinc.com>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
Boqun Feng <boqun.feng@gmail.com>,
linux-riscv <linux-riscv@lists.infradead.org>,
linux-arch <linux-arch@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Guo Ren <guoren@linux.alibaba.com>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH V7 4/5] asm-generic: spinlock: Add combo spinlock (ticket & queued)
Date: Wed, 29 Jun 2022 10:29:37 +0200 [thread overview]
Message-ID: <CAK8P3a3GiMgEJdBg5QQHHD0bDnpR0XwPkAw7=zT7ETzf6-sCmg@mail.gmail.com> (raw)
In-Reply-To: <CAJF2gTTtKiMZJLWBEcRz-4CmNojH0cOgpUYGupLyCXXFjQD_FQ@mail.gmail.com>
On Wed, Jun 29, 2022 at 10:24 AM Guo Ren <guoren@kernel.org> wrote:
> On Wed, Jun 29, 2022 at 3:09 PM Arnd Bergmann <arnd@arndb.de> wrote:
> > On Wed, Jun 29, 2022 at 3:34 AM Waiman Long <longman@redhat.com> wrote:
> >
> > From looking at the header file dependencies on arm64, I know that
> > putting jump labels into core infrastructure like the arch_spin_lock()
> > makes a big mess of indirect includes and measurably slows down
> > the kernel build.
> arm64 needn't combo spinlock, it could use pure qspinlock with keeping
> current header files included.
arm64 has a different problem: there are two separate sets of atomic
instructions, and the decision between those is similarly done using
jump labels. I definitely like the ability to choose between qspinlock
and ticket spinlock on arm64 as well. This can be done as a
compile-time choice, but both of them still depend on jump labels.
Arnd
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next prev parent reply other threads:[~2022-06-29 8:30 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-28 8:17 [PATCH V7 0/5] riscv: Add qspinlock support with combo style guoren
2022-06-28 8:17 ` guoren
2022-06-28 8:17 ` [PATCH V7 1/5] asm-generic: ticket-lock: Remove unnecessary atomic_read guoren
2022-06-28 8:17 ` guoren
2022-06-28 18:05 ` Waiman Long
2022-06-28 18:05 ` Waiman Long
2022-06-29 2:12 ` Guo Ren
2022-06-29 2:12 ` Guo Ren
2022-06-29 8:27 ` David Laight
2022-06-29 8:27 ` David Laight
2022-07-01 15:18 ` Guo Ren
2022-07-01 15:18 ` Guo Ren
2022-07-04 9:52 ` Peter Zijlstra
2022-07-04 9:52 ` Peter Zijlstra
2022-07-04 11:10 ` Guo Ren
2022-07-04 11:10 ` Guo Ren
2022-06-28 8:17 ` [PATCH V7 2/5] asm-generic: ticket-lock: Use the same struct definitions with qspinlock guoren
2022-06-28 8:17 ` guoren
2022-06-28 8:17 ` [PATCH V7 3/5] asm-generic: ticket-lock: Move into ticket_spinlock.h guoren
2022-06-28 8:17 ` guoren
2022-06-28 8:17 ` [PATCH V7 4/5] asm-generic: spinlock: Add combo spinlock (ticket & queued) guoren
2022-06-28 8:17 ` guoren
2022-06-28 18:13 ` Waiman Long
2022-06-28 18:13 ` Waiman Long
2022-06-29 1:17 ` Guo Ren
2022-06-29 1:17 ` Guo Ren
2022-06-29 1:34 ` Waiman Long
2022-06-29 1:34 ` Waiman Long
2022-06-29 2:29 ` Guo Ren
2022-06-29 2:29 ` Guo Ren
2022-06-29 7:08 ` Arnd Bergmann
2022-06-29 7:08 ` Arnd Bergmann
2022-06-29 8:24 ` Guo Ren
2022-06-29 8:24 ` Guo Ren
2022-06-29 8:29 ` Arnd Bergmann [this message]
2022-06-29 8:29 ` Arnd Bergmann
2022-07-01 12:18 ` Guo Ren
2022-07-01 12:18 ` Guo Ren
2022-06-29 12:53 ` Waiman Long
2022-06-29 12:53 ` Waiman Long
2022-07-04 9:57 ` Peter Zijlstra
2022-07-04 9:57 ` Peter Zijlstra
2022-07-04 13:13 ` Guo Ren
2022-07-04 13:13 ` Guo Ren
2022-07-04 13:45 ` Peter Zijlstra
2022-07-04 13:45 ` Peter Zijlstra
2022-06-28 8:17 ` [PATCH V7 5/5] riscv: Add qspinlock support guoren
2022-06-28 8:17 ` guoren
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