linux-kernel - Re: [PATCH v6 2/3] LoongArch: vDSO: Wire up getrandom() vDSO implementation

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Message-ID: <8ba2bb15917480db5cb644570bc7f79cbd6883fd.camel@xry111.site>
Date: Thu, 19 Sep 2024 16:31:19 +0800
From: Xi Ruoyao <xry111@...111.site>
To: Christophe Leroy <christophe.leroy@...roup.eu>, "Jason A . Donenfeld"
	 <Jason@...c4.com>, Huacai Chen <chenhuacai@...nel.org>, WANG Xuerui
	 <kernel@...0n.name>
Cc: linux-crypto@...r.kernel.org, loongarch@...ts.linux.dev, 
	linux-kernel@...r.kernel.org, Jinyang He <hejinyang@...ngson.cn>, Tiezhu
 Yang	 <yangtiezhu@...ngson.cn>, Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH v6 2/3] LoongArch: vDSO: Wire up getrandom() vDSO
 implementation

On Thu, 2024-09-19 at 09:08 +0200, Christophe Leroy wrote:
> I know nothing about Loongarch assembly and execution performance, but I 
> see that GCC groups operations by 4 when building 
> reference_chacha20_blocks() from vdso_test_chacha, see below.
> 
> Shouldn't you do the same and group ROUNDs by 4 just like I did on 
> powerpc ? 
> (https://github.com/torvalds/linux/blob/master/arch/powerpc/kernel/vdso/vgetrandom-chacha.S)

Maybe.  In theory the scheduling would improve the performance.  I'll
measure if the scheduling will make an observable performance
improvement.

-- 
Xi Ruoyao <xry111@...111.site>
School of Aerospace Science and Technology, Xidian University