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From: Gang Li <ligang.bdlg@bytedance.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Kefeng Wang <wangkefeng.wang@huawei.com>,
	Feiyang Chen <chenfeiyang@loongson.cn>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [QUESTION FOR ARM64 TLB] performance issue and implementation difference of TLB flush
Date: Sat, 6 May 2023 10:51:23 +0800	[thread overview]
Message-ID: <9d976db8-b800-ad84-9c67-0afb942934d9@bytedance.com> (raw)
In-Reply-To: <369d1be2-d418-1bfb-bfc2-b25e4e542d76@bytedance.com>

Hi,

On 2023/4/28 17:27, Mark Rutland wrote:> The architecture allows a CPU 
to allocate TLB entries at any time for any
> reason, for any valid translation table entries reachable from the 
> root in
> TTBR{0,1}_ELx. That can be due to speculation, prefetching, and/or other
> reasons.
>

TLB will be allocated due to prefetching or branch prediction. Will it
be invalidated when the prediction fails?

> Due to that, it doesn't matter whether or not a CPU explicitly accesses a
> memory location -- TLB entries can be allocated regardless. 
> Consequently, the
> spinlock doesn't make any difference.
>

And is there any kind of ARM manual or guide that
explains these details to help us programming better?

Thanks a lot for your help.
Gang Li

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  parent reply	other threads:[~2023-05-06  2:53 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-27  3:26 [QUESTION FOR ARM64 TLB] performance issue and implementation difference of TLB flush Gang Li
2023-04-27  7:30 ` Mark Rutland
2023-05-05  9:48   ` Gang Li
2023-05-05 12:28     ` Gang Li
2023-05-16  3:16       ` Gang Li
2023-05-06  2:51     ` Gang Li [this message]
     [not found]       ` <ZFpZAGeEXomG/eKS@FVFF77S0Q05N.cambridge.arm.com>
2023-05-16  7:47         ` Gang Li
2023-05-16 11:51           ` Mark Rutland

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