[PATCH] ARM64: Optimize seq operations

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V1->V2
- Describe the benefit of load acquire vs barriers
- Explain the CONFIG_ARCH_HAS_ACQUIRE_RELEASE option better

Signed-off-by: Christoph Lameter (Ampere) <cl@gentwo.org>
To: Thomas Gleixner <tglx@linutronix.de>
To: Catalin Marinas <catalin.marinas@arm.com>
To: Will Deacon <will@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
To: Ingo Molnar <mingo@redhat.com>
To: Waiman Long <longman@redhat.com>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-arch@vger.kernel.org
---
Changes in v4:
- Remove CONFIG_HAS_ACQUIRE_RELEASE assuming that arches provide
  effective fallbacks for smp_cond_load_acquire / smp_load_acquire
- Use VAL in smp_cond_load_acquire macro
- Link to v3: https://lore.kernel.org/r/20240912-seq_optimize-v3-1-8ee25e04dffa@gentwo.org

Changes in v3:
- Support cond_load_acquire to give the processor a chance to do some
  sort of power down until cacheline changes.
- Better code by Thomas Gleixner
- Link to v2: https://lore.kernel.org/r/20240819-seq_optimize-v2-1-9d0da82b022f@gentwo.org

--- b4-submit-tracking ---
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