Re: [PATCH] KVM: x86: small optimization for is_mtrr_mask calculation

[linmiaohe]

Wanpeng Li <kernellwp@xxxxxxxxx> wrote:
>On Fri, 6 Mar 2020 at 10:23, linmiaohe <linmiaohe@xxxxxxxxxx> wrote:
>>
>> hpa@xxxxxxxxx wrote:
>> >>On March 5, 2020 6:05:40 PM PST, linmiaohe <linmiaohe@xxxxxxxxxx> wrote:
>> >>Hi,
>> >>Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
>> >>Many thanks for suggestion. What do you mean is like this ?
>> >>
>> >>      index = (msr - 0x200) >> 1;
>> >>      is_mtrr_mask = msr & 1;
>> >>
>> >>Thanks again.
>> >
>> >You realize that the compiler will probably produce exactly the same code, right? As such, it is about making the code easy for the human reader.
>> >
>> >Even if it didn't, this code is as far from performance critical as one can possibly get.
>>
>> Yep, it looks gain little. Thanks.
>
>Please post the performance number when you mention optimize XXX later.
>

Sure, I would take care of this. Thanks for your reminder!