Hi Laszlo,
> -----Original Message----- > From: Laszlo Ersek [mailto:[email protected]] > Sent: Wednesday, July 25, 2018 7:47 PM > To: Dong, Eric <[email protected]>; [email protected] > Cc: Ni, Ruiyu <[email protected]> > Subject: Re: [edk2] [Patch v3 2/3] UefiCpuPkg/MpInitLib: Remove StartCount > and volatile definition. > > Hi Eric, > > On 07/25/18 09:50, Eric Dong wrote: > > The StartCount is duplicated with RunningCount, replace it with > > RunningCount. Also the volatile for RunningCount is not needed. > > after staring at this patch for a long time, I think it is correct. > However, I suggest that we improve the commit message, because this patch > actually does three things: > > (1) It removes "volatile" from RunningCount. > > [This is OK, because only the BSP modifies it.] > > (2) [This is the tricky part.] > > When we detect a timeout in CheckAllAPs(), and collect the list of failed > CPUs, > the size of the list is derived from the following difference, before the > patch: > > StartCount - FinishedCount > > where "StartCount" is set by the BSP at startup, and FinishedCount is > incremented by the APs themselves. > I think FinishedCount used here is a typo. What the logic from the code context here is want to get the failed Aps and return them. So it should use RunningCount here, right? Also the FinishedCount may be bigger than StartCount if many Aps has been disabled. Right? > The patch replaces this difference with > > StartCount - RunningCount > > that is, the difference is no more calculated from the BSP's startup counter > and the AP's shared finish counter, but from the RunningCount measurement > that the BSP does itself, in CheckAllAPs(). > > [This change is OK to me as well, but we should be clear about it.] > > (3) Finally, the patch changes the meaning of RunningCount. Before the patch, > we have: > > - StartCount: the number of APs the BSP stars up, > - RunningCount: the number of finished APs that the BSP collected > > After the patch, StartCount is removed, and RunningCount is *redefined* as > the following difference: > > OLD_StartCount - OLD_RunningCount > > Giving the number of APs that the BSP started up but hasn't collected yet. > > [This change looks good to me as well.] > > ----*---- > > Importantly, what we see in the AllocatePool() argument, is the > *composition* of steps (2) and (3). > > If you agree, can you please update the commit message to include my points > (1) through (3)? It's OK if you leave out my remarks in brackets []. Agreed. Will use your content when commit the changes. Thanks, Eric > > No need to repost just because of this, of course. > > Thanks! > Laszlo > > > > > Cc: Laszlo Ersek <[email protected]> > > Cc: Ruiyu Ni <[email protected]> > > Contributed-under: TianoCore Contribution Agreement 1.1 > > Signed-off-by: Eric Dong <[email protected]> > > --- > > UefiCpuPkg/Library/MpInitLib/MpLib.c | 11 +++++------ > > UefiCpuPkg/Library/MpInitLib/MpLib.h | 3 +-- > > 2 files changed, 6 insertions(+), 8 deletions(-) > > > > diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c > > b/UefiCpuPkg/Library/MpInitLib/MpLib.c > > index ff09a0e9e7..0e57cc86bf 100644 > > --- a/UefiCpuPkg/Library/MpInitLib/MpLib.c > > +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c > > @@ -1424,7 +1424,7 @@ CheckAllAPs ( > > // value of state after setting the it to CpuStateIdle, so BSP can > > safely > make use of its value. > > // > > if (GetApState(CpuData) == CpuStateIdle) { > > - CpuMpData->RunningCount ++; > > + CpuMpData->RunningCount --; > > CpuMpData->CpuData[ProcessorNumber].Waiting = FALSE; > > > > // > > @@ -1449,7 +1449,7 @@ CheckAllAPs ( > > // > > // If all APs finish, return EFI_SUCCESS. > > // > > - if (CpuMpData->RunningCount == CpuMpData->StartCount) { > > + if (CpuMpData->RunningCount == 0) { > > return EFI_SUCCESS; > > } > > > > @@ -1466,7 +1466,7 @@ CheckAllAPs ( > > // > > if (CpuMpData->FailedCpuList != NULL) { > > *CpuMpData->FailedCpuList = > > - AllocatePool ((CpuMpData->StartCount - CpuMpData->FinishedCount > + 1) * sizeof (UINTN)); > > + AllocatePool ((CpuMpData->RunningCount + 1) * sizeof > > + (UINTN)); > > ASSERT (*CpuMpData->FailedCpuList != NULL); > > } > > ListIndex = 0; > > @@ -2212,7 +2212,7 @@ StartupAllAPsWorker ( > > return EFI_NOT_STARTED; > > } > > > > - CpuMpData->StartCount = 0; > > + CpuMpData->RunningCount = 0; > > for (ProcessorNumber = 0; ProcessorNumber < ProcessorCount; > ProcessorNumber++) { > > CpuData = &CpuMpData->CpuData[ProcessorNumber]; > > CpuData->Waiting = FALSE; > > @@ -2222,7 +2222,7 @@ StartupAllAPsWorker ( > > // Mark this processor as responsible for current calling. > > // > > CpuData->Waiting = TRUE; > > - CpuMpData->StartCount++; > > + CpuMpData->RunningCount++; > > } > > } > > } > > @@ -2231,7 +2231,6 @@ StartupAllAPsWorker ( > > CpuMpData->ProcArguments = ProcedureArgument; > > CpuMpData->SingleThread = SingleThread; > > CpuMpData->FinishedCount = 0; > > - CpuMpData->RunningCount = 0; > > CpuMpData->FailedCpuList = FailedCpuList; > > CpuMpData->ExpectedTime = CalculateTimeout ( > > TimeoutInMicroseconds, diff --git > > a/UefiCpuPkg/Library/MpInitLib/MpLib.h > > b/UefiCpuPkg/Library/MpInitLib/MpLib.h > > index 962bce685d..5002b7e9c0 100644 > > --- a/UefiCpuPkg/Library/MpInitLib/MpLib.h > > +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.h > > @@ -211,9 +211,8 @@ struct _CPU_MP_DATA { > > UINTN BackupBuffer; > > UINTN BackupBufferSize; > > > > - volatile UINT32 StartCount; > > volatile UINT32 FinishedCount; > > - volatile UINT32 RunningCount; > > + UINT32 RunningCount; > > BOOLEAN SingleThread; > > EFI_AP_PROCEDURE Procedure; > > VOID *ProcArguments; > > _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
