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: [RFT PATCH] riscv: mremap speedup - enable HAVE_MOVE_PUD and HAVE_MOVE_PMD
Date: Sat, 17 Apr 2021 00:37:22 +0800 [thread overview]
Message-ID: <20210417003539.5bceabc2@xhacker> (raw)
From: Jisheng Zhang <jszhang@kernel.org>
HAVE_MOVE_PUD enables remapping pages at the PUD level if both the source
and destination addresses are PUD-aligned.
HAVE_MOVE_PMD does similar speedup on the PMD level.
With HAVE_MOVE_PUD enabled, there is about a 143x improvement on qemu
With HAVE_MOVE_PMD enabled, there is about a 5x improvement on qemu
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
Hi all,
After reading the risc-v privileged spec, I think it's safe to support
the HAVE_MOVE_PUD and HAVE_MOVE_PMD optimization on riscv. The patch passed
the mremap_test on QEMU. However this can't be tested on real HW due to lack
of HW boards, this is the reason why I mark this patch as RFT. I hope I can
buy a sipeed Allwiner D1 SoC powered SBC soon, at least I can test
HAVE_MOVE_PMD. Helping me to test on real HW is appreciated!
Thanks
arch/riscv/Kconfig | 2 ++
arch/riscv/include/asm/pgtable.h | 12 ++++++++++++
2 files changed, 14 insertions(+)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index e8074d248457..37660de68b00 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -80,6 +80,8 @@ config RISCV
select HAVE_KPROBES
select HAVE_KPROBES_ON_FTRACE
select HAVE_KRETPROBES
+ select HAVE_MOVE_PMD
+ select HAVE_MOVE_PUD
select HAVE_PCI
select HAVE_PERF_EVENTS
select HAVE_PERF_REGS
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index ebf817c1bdf4..287733b95d10 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -360,6 +360,18 @@ static inline void set_pte_at(struct mm_struct *mm,
set_pte(ptep, pteval);
}
+static inline void set_pmd_at(struct mm_struct *mm, unsigned long addr,
+ pmd_t *pmdp, pmd_t pmd)
+{
+ set_pmd(pmdp, pmd);
+}
+
+static inline void set_pud_at(struct mm_struct *mm, unsigned long addr,
+ pud_t *pudp, pud_t pud)
+{
+ set_pud(pudp, pud);
+}
+
static inline void pte_clear(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
{
--
2.31.0
next reply other threads:[~2021-04-16 16:42 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-16 16:37 Jisheng Zhang [this message]
2021-05-22 15:58 ` [RFT PATCH] riscv: mremap speedup - enable HAVE_MOVE_PUD and HAVE_MOVE_PMD Palmer Dabbelt
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