From: Jisheng Zhang <jszhang3@mail.ustc.edu.cn>
To: Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>
Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH] riscv: Optimize switch_mm by passing "cpu" to flush_icache_deferred()
Date: Wed, 12 May 2021 01:42:31 +0800 [thread overview]
Message-ID: <20210512014231.466aff04@xhacker> (raw)
From: Jisheng Zhang <jszhang@kernel.org>
Directly passing the cpu to flush_icache_deferred() rather than calling
smp_processor_id() again.
Here are some performance numbers:
With a run of hackbench 30 times on a single core riscv64 Qemu instance
with 1GB memory:
without this patch: mean 36.934
with this patch: mean 36.104 (improved by 2.24%)
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
arch/riscv/mm/context.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/arch/riscv/mm/context.c b/arch/riscv/mm/context.c
index 68aa312fc352..6d445f2888ec 100644
--- a/arch/riscv/mm/context.c
+++ b/arch/riscv/mm/context.c
@@ -281,10 +281,9 @@ static inline void set_mm(struct mm_struct *mm, unsigned int cpu)
* actually performs that local instruction cache flush, which implicitly only
* refers to the current hart.
*/
-static inline void flush_icache_deferred(struct mm_struct *mm)
+static inline void flush_icache_deferred(struct mm_struct *mm, unsigned int cpu)
{
#ifdef CONFIG_SMP
- unsigned int cpu = smp_processor_id();
cpumask_t *mask = &mm->context.icache_stale_mask;
if (cpumask_test_cpu(cpu, mask)) {
@@ -320,5 +319,5 @@ void switch_mm(struct mm_struct *prev, struct mm_struct *next,
set_mm(next, cpu);
- flush_icache_deferred(next);
+ flush_icache_deferred(next, cpu);
}
--
2.31.0
next reply other threads:[~2021-05-11 17:48 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-11 17:42 Jisheng Zhang [this message]
2021-05-26 5:30 ` [PATCH] riscv: Optimize switch_mm by passing "cpu" to flush_icache_deferred() Palmer Dabbelt
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