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From: Eric Biggers <ebiggers@kernel.org>
To: Tony W Wang-oc <TonyWWang-oc@zhaoxin.com>
Cc: herbert@gondor.apana.org.au, davem@davemloft.net,
	tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
	x86@kernel.org, hpa@zytor.com, linux-crypto@vger.kernel.org,
	linux-kernel@vger.kernel.org, TimGuo-oc@zhaoxin.com,
	CooperYan@zhaoxin.com, QiyuanWang@zhaoxin.com,
	HerryYang@zhaoxin.com, CobeChen@zhaoxin.com,
	SilviaZhao@zhaoxin.com
Subject: Re: [PATCH] crypto: x86/crc32c-intel - Don't match some Zhaoxin CPUs
Date: Fri, 11 Dec 2020 09:43:57 -0800	[thread overview]
Message-ID: <X9Ov3RWDpUik7gXo@sol.localdomain> (raw)
In-Reply-To: <1607686144-2604-1-git-send-email-TonyWWang-oc@zhaoxin.com>

On Fri, Dec 11, 2020 at 07:29:04PM +0800, Tony W Wang-oc wrote:
> The driver crc32c-intel match CPUs supporting X86_FEATURE_XMM4_2.
> On platforms with Zhaoxin CPUs supporting this X86 feature, When
> crc32c-intel and crc32c-generic are both registered, system will
> use crc32c-intel because its .cra_priority is greater than
> crc32c-generic. This case expect to use crc32c-generic driver for
> some Zhaoxin CPUs to get performance gain, So remove these Zhaoxin
> CPUs support from crc32c-intel.
> 
> Signed-off-by: Tony W Wang-oc <TonyWWang-oc@zhaoxin.com>

Does this mean that the performance of the crc32c instruction on those CPUs is
actually slower than a regular C implementation?  That's very weird.

- Eric

  parent reply	other threads:[~2020-12-11 19:25 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-11 11:29 [PATCH] crypto: x86/crc32c-intel - Don't match some Zhaoxin CPUs Tony W Wang-oc
2020-12-11 13:00 ` Peter Zijlstra
2020-12-12  4:32   ` Tony W Wang-oc
2020-12-11 17:43 ` Eric Biggers [this message]
2020-12-12  9:36   ` Ard Biesheuvel
2020-12-12 10:54     ` Ard Biesheuvel
2020-12-14  2:29       ` Tony W Wang-oc
2020-12-14  2:28   ` Tony W Wang-oc
2020-12-14 20:41     ` Eric Biggers
2020-12-15  2:15       ` Tony W Wang-oc
2020-12-15 17:56         ` Eric Biggers
2020-12-21  2:46           ` tonywwang-oc
2020-12-21 19:27             ` hpa
2020-12-22  3:01               ` tonywwang-oc
2020-12-22  4:54                 ` hpa
2021-01-07  6:23                   ` Tony W Wang-oc
2020-12-14  3:59 Tony W Wang-oc
2020-12-15  8:58 ` Peter Zijlstra
2020-12-15 10:02   ` Tony W Wang-oc
2020-12-15 10:28 Tony W Wang-oc
2021-01-02 21:12 ` Herbert Xu
2021-01-07  6:27   ` Tony W Wang-oc

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