linux-kernel - Re: [PATCH 4/4] riscv: enable HAVE_FAST_GUP if MMU

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Message-ID: <509f3dd7-1c38-4b98-b21b-28d50399a344@ghiti.fr>
Date: Thu, 4 Jan 2024 11:46:14 +0100
From: Alexandre Ghiti <alex@...ti.fr>
To: Jisheng Zhang <jszhang@...nel.org>
Cc: Paul Walmsley <paul.walmsley@...ive.com>,
 Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
 Will Deacon <will@...nel.org>,
 "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
 Andrew Morton <akpm@...ux-foundation.org>, Nick Piggin <npiggin@...il.com>,
 Peter Zijlstra <peterz@...radead.org>, linux-riscv@...ts.infradead.org,
 linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH 4/4] riscv: enable HAVE_FAST_GUP if MMU

On 02/01/2024 04:25, Jisheng Zhang wrote:
> On Sun, Dec 31, 2023 at 07:37:33AM +0100, Alexandre Ghiti wrote:
>> On 19/12/2023 18:50, Jisheng Zhang wrote:
>>> Activate the fast gup for riscv mmu platforms. Here are some
>>> GUP_FAST_BENCHMARK performance numbers:
>>>
>>> Before the patch:
>>> GUP_FAST_BENCHMARK: Time: get:53203 put:5085 us
>>>
>>> After the patch:
>>> GUP_FAST_BENCHMARK: Time: get:17711 put:5060 us
>>
>> On which platform did you run this benchmark?
> T-HEAD th1520(cpufreq isn't enabled since the clk/pll isn't upstreamed,
> so cpu is running at the default freq set by u-boot)
>>
>>> The get time is reduced by 66.7%! IOW, 3x get speed!
>>
>> Well done!
>>
>> Thanks,
>>
>> Alex
>>
>>
>>> Signed-off-by: Jisheng Zhang <jszhang@...nel.org>
>>> ---
>>>    arch/riscv/Kconfig               | 1 +
>>>    arch/riscv/include/asm/pgtable.h | 6 ++++++
>>>    2 files changed, 7 insertions(+)
>>>
>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>>> index d3555173d9f4..04df9920282d 100644
>>> --- a/arch/riscv/Kconfig
>>> +++ b/arch/riscv/Kconfig
>>> @@ -119,6 +119,7 @@ config RISCV
>>>    	select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
>>>    	select HAVE_FUNCTION_TRACER if !XIP_KERNEL && !PREEMPTION
>>>    	select HAVE_EBPF_JIT if MMU
>>> +	select HAVE_FAST_GUP if MMU
>>>    	select HAVE_FUNCTION_ARG_ACCESS_API
>>>    	select HAVE_FUNCTION_ERROR_INJECTION
>>>    	select HAVE_GCC_PLUGINS
>>> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
>>> index ab00235b018f..c6eb214139e6 100644
>>> --- a/arch/riscv/include/asm/pgtable.h
>>> +++ b/arch/riscv/include/asm/pgtable.h
>>> @@ -673,6 +673,12 @@ static inline int pmd_write(pmd_t pmd)
>>>    	return pte_write(pmd_pte(pmd));
>>>    }
>>> +#define pud_write pud_write
>>> +static inline int pud_write(pud_t pud)
>>> +{
>>> +	return pte_write(pud_pte(pud));
>>> +}
>>> +
>>>    static inline int pmd_dirty(pmd_t pmd)
>>>    {
>>>    	return pte_dirty(pmd_pte(pmd));

Thanks, you can add:

Reviewed-by: Alexandre Ghiti <alexghiti@...osinc.com>

Thanks,

Alex

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> linux-riscv@...ts.infradead.org
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