From: Atish Patra <atish.patra@wdc.com>
To: linux-kernel@vger.kernel.org
Cc: Atish Patra <atish.patra@wdc.com>,
Albert Ou <aou@eecs.berkeley.edu>,
linux-riscv@lists.infradead.org,
Palmer Dabbelt <palmer@sifive.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Christoph Hellwig <hch@lst.de>, Anup Patel <Anup.Patel@wdc.com>
Subject: [PATCH v4 2/3] RISC-V: Issue a local tlbflush if possible.
Date: Thu, 22 Aug 2019 00:51:50 -0700 [thread overview]
Message-ID: <20190822075151.24838-3-atish.patra@wdc.com> (raw)
In-Reply-To: <20190822075151.24838-1-atish.patra@wdc.com>
In RISC-V, tlb flush happens via SBI which is expensive. If the local
cpu is the only cpu in cpumask, there is no need to invoke a SBI call.
Just do a local flush and return.
Signed-off-by: Atish Patra <atish.patra@wdc.com>
---
arch/riscv/mm/tlbflush.c | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)
diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
index 1293b8017ee0..8172fbf46123 100644
--- a/arch/riscv/mm/tlbflush.c
+++ b/arch/riscv/mm/tlbflush.c
@@ -2,6 +2,7 @@
#include <linux/mm.h>
#include <linux/smp.h>
+#include <linux/sched.h>
#include <asm/sbi.h>
void flush_tlb_all(void)
@@ -9,16 +10,30 @@ void flush_tlb_all(void)
sbi_remote_sfence_vma(NULL, 0, -1);
}
+/*
+ * This function must not be called with cmask being null.
+ * Kernel may panic if cmask is NULL.
+ */
static void __sbi_tlb_flush_range(struct cpumask *cmask, unsigned long start,
unsigned long size)
{
struct cpumask hmask;
+ unsigned int cpuid;
if (cpumask_empty(cmask))
return;
- riscv_cpuid_to_hartid_mask(cmask, &hmask);
- sbi_remote_sfence_vma(hmask.bits, start, size);
+ cpuid = get_cpu();
+
+ if (cpumask_any_but(cmask, cpuid) >= nr_cpu_ids) {
+ /* local cpu is the only cpu present in cpumask */
+ local_flush_tlb_all();
+ } else {
+ riscv_cpuid_to_hartid_mask(cmask, &hmask);
+ sbi_remote_sfence_vma(cpumask_bits(&hmask), start, size);
+ }
+
+ put_cpu();
}
void flush_tlb_mm(struct mm_struct *mm)
--
2.21.0
next prev parent reply other threads:[~2019-08-22 7:59 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-22 7:51 [PATCH v4 0/3] Optimize tlbflush path Atish Patra
2019-08-22 7:51 ` [PATCH v4 1/3] RISC-V: Do not invoke SBI call if cpumask is empty Atish Patra
2019-08-22 8:10 ` Christoph Hellwig
2019-08-22 7:51 ` Atish Patra [this message]
2019-08-22 8:10 ` [PATCH v4 2/3] RISC-V: Issue a local tlbflush if possible Christoph Hellwig
2019-08-22 7:51 ` [PATCH v4 3/3] RISC-V: Issue a tlb page flush " Atish Patra
2019-08-22 8:11 ` Christoph Hellwig
2019-08-22 18:31 ` Atish Patra
2019-08-31 2:50 ` [PATCH v4 0/3] Optimize tlbflush path Paul Walmsley
2019-09-28 4:23 ` Atish Patra
2019-10-25 3:09 ` Paul Walmsley
2019-10-31 15:13 ` Atish Patra
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