Re: [Patch v2] UefiCpuPkg/MpInitLib: Optimize get processor number performance.

["Ni, Ruiyu" <ruiyu.ni@intel.com>]

Reviewed-by: Ruiyu Ni <Ruiyu.ni@intel.com>

Thanks/Ray

> -----Original Message-----
> From: Dong, Eric
> Sent: Wednesday, July 18, 2018 1:19 PM
> To: edk2-devel@lists.01.org
> Cc: Ni, Ruiyu <ruiyu.ni@intel.com>; Jeff Fan <vanjeff_919@hotmail.com>;
> Laszlo Ersek <lersek@redhat.com>
> Subject: [Patch v2] UefiCpuPkg/MpInitLib: Optimize get processor number
> performance.
> 
> Current function has low performance because it calls GetApicId many times.
> 
> New logic call GetApicId once and base on this value to search the processor.
> 
> V2 changes:
> Rollback V1 change which base on stack info to get AP index because this
> solution may return error AP index if stack buffer overflow.
> 
> Cc: Ruiyu Ni <ruiyu.ni@intel.com>
> Cc: Jeff Fan <vanjeff_919@hotmail.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Eric Dong <eric.dong@intel.com>
> ---
>  UefiCpuPkg/Library/MpInitLib/MpLib.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c
> b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> index 722db2a01f..0bb0582985 100644
> --- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
> +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> @@ -435,16 +435,19 @@ GetProcessorNumber (
>    UINTN                   TotalProcessorNumber;
>    UINTN                   Index;
>    CPU_INFO_IN_HOB         *CpuInfoInHob;
> +  UINT32                  CurrentApicId;
> 
>    CpuInfoInHob = (CPU_INFO_IN_HOB *) (UINTN) CpuMpData-
> >CpuInfoInHob;
> 
>    TotalProcessorNumber = CpuMpData->CpuCount;
> +  CurrentApicId = GetApicId ();
>    for (Index = 0; Index < TotalProcessorNumber; Index ++) {
> -    if (CpuInfoInHob[Index].ApicId == GetApicId ()) {
> +    if (CpuInfoInHob[Index].ApicId == CurrentApicId) {
>        *ProcessorNumber = Index;
>        return EFI_SUCCESS;
>      }
>    }
> +
>    return EFI_NOT_FOUND;
>  }
> 
> --
> 2.15.0.windows.1