Re: [PATCH] crypto: x86/crc32c-intel - Don't match some Zhaoxin CPUs

[Tony W Wang-oc]

On 12/12/2020 01:43, Eric Biggers wrote:
> 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@xxxxxxxxxxx>
> 
> 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.
> 

>From the lmbench3 Create and Delete file test on those chips, I think yes.

sincerely
Tony