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From: Zhenyu Ye <yezhenyu2@huawei.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: <linux-arch@vger.kernel.org>, <suzuki.poulose@arm.com>,
	<maz@kernel.org>, <linux-kernel@vger.kernel.org>,
	<xiexiangyou@huawei.com>, <steven.price@arm.com>,
	<zhangshaokun@hisilicon.com>, <linux-mm@kvack.org>,
	<arm@kernel.org>, <prime.zeng@hisilicon.com>,
	<guohanjun@huawei.com>, <olof@lixom.net>,
	<kuhn.chenqun@huawei.com>, <will@kernel.org>,
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [RFC PATCH v3 2/2] arm64: tlb: Use the TLBI RANGE feature in arm64
Date: Mon, 1 Jun 2020 22:57:35 +0800	[thread overview]
Message-ID: <a159dd5a-7189-308f-9ebc-98f0eadca852@huawei.com> (raw)
In-Reply-To: <20200520170759.GE18302@gaia>

Hi Catalin,

I have sent the v4 of this series [1] and combine the two function with
a single loop.  See codes for details.

[1] https://lore.kernel.org/linux-arm-kernel/20200601144713.2222-1-yezhenyu2@huawei.com/

On 2020/5/21 1:08, Catalin Marinas wrote:
>> This optimization is only effective when the range is a multiple of 256KB
>> (when the page size is 4KB), and I'm worried about the performance
>> of ilog2().  I traced the __flush_tlb_range() last year and found that in
>> most cases the range is less than 256K (see details in [1]).
> 
> THP or hugetlbfs would exercise bigger strides but I guess it depends on
> the use-case. ilog2() should be reduced to a few instructions on arm64
> AFAICT (haven't tried but it should use the CLZ instruction).
> 

Not bigger than 256K, but the range must be a integer multiple of 256KB,
so I still start from scale 0.

Thanks,
Zhenyu



  reply	other threads:[~2020-06-01 14:57 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-14 11:28 [RFC PATCH v3 0/2] arm64: tlb: add support for TLBI RANGE instructions Zhenyu Ye
2020-04-14 11:28 ` [RFC PATCH v3 1/2] arm64: tlb: Detect the ARMv8.4 TLBI RANGE feature Zhenyu Ye
2020-05-05 10:14   ` Mark Rutland
2020-05-11 12:25     ` Zhenyu Ye
2020-05-18  4:22       ` Anshuman Khandual
2020-05-18 12:29         ` Zhenyu Ye
2020-04-14 11:28 ` [RFC PATCH v3 2/2] arm64: tlb: Use the TLBI RANGE feature in arm64 Zhenyu Ye
2020-05-14 15:28   ` Catalin Marinas
2020-05-18 12:21     ` Zhenyu Ye
2020-05-20 17:08       ` Catalin Marinas
2020-06-01 14:57         ` Zhenyu Ye [this message]
2020-06-09 13:26       ` Zhenyu Ye

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