Files
system76-edk2/UefiCpuPkg/Library/MpInitLib/DxeMpInitLib.inf
Hao A Wu a1c35ff312 UefiCpuPkg/MpInitLib DXE: Add PCD to control AP status check interval
REF:https://bugzilla.tianocore.org/show_bug.cgi?id=2627

The commit will introduce a static PCD to specify the periodic interval
for checking the AP status when MP services StartupAllAPs() and
StartupThisAP() are being executed in a non-blocking manner. Or in other
words, specifies the interval for callback function CheckApsStatus().

The purpose is to provide the platform owners with the ability to choose
the proper interval value to trigger CheckApsStatus() according to:
A) The number of processors in the system;
B) How MP services (StartupAllAPs & StartupThisAP) being used.

Setting the PCD to a small value means the AP status check callback will
be triggered more frequently, it can benefit the performance for the case
when the BSP uses WaitForEvent() or uses CheckEvent() in a loop to wait
for AP(s) to complete the task, especially when the task can be finished
considerably fast on AP(s).

An example is within function CpuFeaturesInitialize() under
UefiCpuPkg/Library/RegisterCpuFeaturesLib/DxeRegisterCpuFeaturesLib.c,
where BSP will perform the same task with APs and requires all the
processors to finish the task before BSP proceeds to its next task.

Setting the PCD to a big value, on the other hand, can reduce the impact
on BSP by the time being consumed in CheckApsStatus(), especially when the
number of processors is huge so that the time consumed in CheckApsStatus()
is not negligible.

The type of the PCD is UINT32, which means the maximum possible interval
value can be set to:
4,294,967,295 microseconds = 4,295 seconds = 71.58 minutes = 1.19 hours
which should be sufficient for usage.

For least impact, the default value of the new PCD will be the same with
the current interval value. It will be set to 100,000 microseconds, which
is 100 milliseconds.

Unitest done:
A) OS boot successfully;
B) Use debug message to confirm the 'TriggerTime' parameter for the
   'SetTimer' service is the same before & after this patch.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Brian J. Johnson <brian.johnson@hpe.com>
Signed-off-by: Hao A Wu <hao.a.wu@intel.com>
Reviewed-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
2020-03-27 00:46:39 +00:00

74 lines
2.3 KiB
INI

## @file
# MP Initialize Library instance for DXE driver.
#
# Copyright (c) 2016 - 2020, Intel Corporation. All rights reserved.<BR>
# SPDX-License-Identifier: BSD-2-Clause-Patent
#
##
[Defines]
INF_VERSION = 0x00010005
BASE_NAME = DxeMpInitLib
MODULE_UNI_FILE = DxeMpInitLib.uni
FILE_GUID = B88F7146-9834-4c55-BFAC-481CC0C33736
MODULE_TYPE = DXE_DRIVER
VERSION_STRING = 1.1
LIBRARY_CLASS = MpInitLib|DXE_DRIVER
#
# The following information is for reference only and not required by the build tools.
#
# VALID_ARCHITECTURES = IA32 X64
#
[Sources.IA32]
Ia32/MpEqu.inc
Ia32/MpFuncs.nasm
[Sources.X64]
X64/MpEqu.inc
X64/MpFuncs.nasm
[Sources.common]
DxeMpLib.c
MpLib.c
MpLib.h
Microcode.c
[Packages]
MdePkg/MdePkg.dec
MdeModulePkg/MdeModulePkg.dec
UefiCpuPkg/UefiCpuPkg.dec
[LibraryClasses]
BaseLib
LocalApicLib
MemoryAllocationLib
HobLib
MtrrLib
CpuLib
UefiCpuLib
UefiBootServicesTableLib
DebugAgentLib
SynchronizationLib
[Protocols]
gEfiTimerArchProtocolGuid ## SOMETIMES_CONSUMES
[Guids]
gEfiEventExitBootServicesGuid ## CONSUMES ## Event
gEfiEventLegacyBootGuid ## SOMETIMES_CONSUMES ## Event
gEdkiiMicrocodePatchHobGuid ## SOMETIMES_CONSUMES ## HOB
[Pcd]
gUefiCpuPkgTokenSpaceGuid.PcdCpuMaxLogicalProcessorNumber ## CONSUMES
gUefiCpuPkgTokenSpaceGuid.PcdCpuBootLogicalProcessorNumber ## CONSUMES
gUefiCpuPkgTokenSpaceGuid.PcdCpuApInitTimeOutInMicroSeconds ## SOMETIMES_CONSUMES
gUefiCpuPkgTokenSpaceGuid.PcdCpuApStackSize ## CONSUMES
gUefiCpuPkgTokenSpaceGuid.PcdCpuMicrocodePatchAddress ## CONSUMES
gUefiCpuPkgTokenSpaceGuid.PcdCpuMicrocodePatchRegionSize ## CONSUMES
gUefiCpuPkgTokenSpaceGuid.PcdCpuApLoopMode ## CONSUMES
gUefiCpuPkgTokenSpaceGuid.PcdCpuApTargetCstate ## SOMETIMES_CONSUMES
gUefiCpuPkgTokenSpaceGuid.PcdCpuApStatusCheckIntervalInMicroSeconds ## CONSUMES
gEfiMdeModulePkgTokenSpaceGuid.PcdCpuStackGuard ## CONSUMES