From: Boqun Feng <boqun@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Catalin Marinas" <catalin.marinas@arm.com>,
"Will Deacon" <will@kernel.org>,
"Jonas Bonn" <jonas@southpole.se>,
"Stefan Kristiansson" <stefan.kristiansson@saunalahti.fi>,
"Stafford Horne" <shorne@gmail.com>,
"Heiko Carstens" <hca@linux.ibm.com>,
"Vasily Gorbik" <gor@linux.ibm.com>,
"Alexander Gordeev" <agordeev@linux.ibm.com>,
"Christian Borntraeger" <borntraeger@linux.ibm.com>,
"Sven Schnelle" <svens@linux.ibm.com>,
"Thomas Gleixner" <tglx@kernel.org>,
"Ingo Molnar" <mingo@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
"Arnd Bergmann" <arnd@arndb.de>,
"Juri Lelli" <juri.lelli@redhat.com>,
"Vincent Guittot" <vincent.guittot@linaro.org>,
"Dietmar Eggemann" <dietmar.eggemann@arm.com>,
"Steven Rostedt" <rostedt@goodmis.org>,
"Ben Segall" <bsegall@google.com>, "Mel Gorman" <mgorman@suse.de>,
"Valentin Schneider" <vschneid@redhat.com>,
"K Prateek Nayak" <kprateek.nayak@amd.com>,
"Boqun Feng" <boqun@kernel.org>,
"Waiman Long" <longman@redhat.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Miguel Ojeda" <ojeda@kernel.org>, "Gary Guo" <gary@garyguo.net>,
"Björn Roy Baron" <bjorn3_gh@protonmail.com>,
"Benno Lossin" <lossin@kernel.org>,
"Andreas Hindborg" <a.hindborg@kernel.org>,
"Alice Ryhl" <aliceryhl@google.com>,
"Trevor Gross" <tmgross@umich.edu>,
"Danilo Krummrich" <dakr@kernel.org>,
"Jinjie Ruan" <ruanjinjie@huawei.com>,
"Ada Couprie Diaz" <ada.coupriediaz@arm.com>,
"Lyude Paul" <lyude@redhat.com>,
"Sohil Mehta" <sohil.mehta@intel.com>,
"Pawan Gupta" <pawan.kumar.gupta@linux.intel.com>,
"Xin Li (Intel)" <xin@zytor.com>,
"Sean Christopherson" <seanjc@google.com>,
"Nikunj A Dadhania" <nikunj@amd.com>,
"Joel Fernandes" <joelagnelf@nvidia.com>,
"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
"Randy Dunlap" <rdunlap@infradead.org>,
"Yury Norov" <ynorov@nvidia.com>,
"Sebastian Andrzej Siewior" <bigeasy@linutronix.de>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-openrisc@vger.kernel.org,
linux-s390@vger.kernel.org, linux-arch@vger.kernel.org,
rust-for-linux@vger.kernel.org
Subject: [PATCH 11/11] arm64: sched/preempt: Enable PREEMPT_COUNT_64BIT
Date: Thu, 7 May 2026 21:21:11 -0700 [thread overview]
Message-ID: <20260508042111.24358-12-boqun@kernel.org> (raw)
In-Reply-To: <20260508042111.24358-1-boqun@kernel.org>
ARM64 already uses 64bit preempt count and the need reschedule bit is
maintained in a separate 32bit than the preempt count. Therefore preempt
count has enough bits to represent 16 level of NMI nesting, hence enable
it for ARM64. This saves a per-CPU variable and additional instructions
in the NMI path.
Signed-off-by: Boqun Feng <boqun@kernel.org>
---
arch/arm64/Kconfig | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index fe60738e5943..1ed5173872fc 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -248,6 +248,7 @@ config ARM64
select PCI_SYSCALL if PCI
select POWER_RESET
select POWER_SUPPLY
+ select PREEMPT_COUNT_64BIT
select SPARSE_IRQ
select SWIOTLB
select SYSCTL_EXCEPTION_TRACE
--
2.50.1 (Apple Git-155)
next prev parent reply other threads:[~2026-05-08 4:21 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-08 4:21 [PATCH 00/11] Refcounted interrupt disable and SpinLockIrq for rust (Part 1) Boqun Feng
2026-05-08 4:21 ` [PATCH 01/11] preempt: Introduce HARDIRQ_DISABLE_BITS Boqun Feng
2026-05-12 16:28 ` Steven Rostedt
2026-05-08 4:21 ` [PATCH 02/11] preempt: Track NMI nesting to separate per-CPU counter Boqun Feng
2026-05-12 16:30 ` Steven Rostedt
2026-05-12 19:22 ` Joel Fernandes
2026-05-12 22:16 ` Boqun Feng
2026-05-12 23:33 ` Joel Fernandes
2026-05-08 4:21 ` [PATCH 03/11] preempt: Introduce __preempt_count_{sub, add}_return() Boqun Feng
2026-05-09 18:09 ` Heiko Carstens
2026-05-08 4:21 ` [PATCH 04/11] openrisc: Include <linux/cpumask.h> in smp.h Boqun Feng
2026-05-08 4:21 ` [PATCH 05/11] irq & spin_lock: Add counted interrupt disabling/enabling Boqun Feng
2026-05-08 4:21 ` [PATCH 06/11] irq: Add KUnit test for refcounted interrupt enable/disable Boqun Feng
2026-05-08 4:21 ` [PATCH 07/11] locking: Switch to _irq_{disable,enable}() variants in cleanup guards Boqun Feng
2026-05-08 4:21 ` [PATCH 08/11] sched: Remove the unused preempt_offset parameter of __cant_sleep() Boqun Feng
2026-05-08 4:21 ` [PATCH 09/11] sched: Avoid signed comparison of preempt_count() in __cant_migrate() Boqun Feng
2026-05-08 4:21 ` [PATCH 10/11] preempt: Introduce PREEMPT_COUNT_64BIT Boqun Feng
2026-05-08 4:21 ` Boqun Feng [this message]
2026-05-08 8:22 ` [PATCH 11/11] arm64: sched/preempt: Enable PREEMPT_COUNT_64BIT Mark Rutland
2026-05-08 14:48 ` Boqun Feng
2026-05-09 18:12 ` [PATCH 00/11] Refcounted interrupt disable and SpinLockIrq for rust (Part 1) Heiko Carstens
2026-05-09 18:21 ` Boqun Feng
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