subject:"\[edk2\] \[PATCH\] PcAtChipsetPkg AcpiTimerLib\: Get more accurate TSC Frequency"

Re: [edk2] [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC Frequency

2016-08-12 Thread Kinney, Michael D

Paolo,

That is a good idea to find factors of ACPI_TIMER_FREQUENCY 3579545 Hz
and find a value that is close to 100 uS for calibration.  The pair you
found 343 * 10436 = 3579548 Hz.  If we look at frequencies lower and 
higher than ACPI_TIMER_FREQUENCY, the value 3579543 has many more factors
and is only 2 Hz from the target.

Number Factors
===
35795421, 2, 67, 134, 26713, 53426, 1789771, 3579542
 
35795431, 3, 9, 11, 19, 33, 57, 99, 121, 171, 173, 209, 363, 
   519, 627, 1089, 1557, 1881, 1903, 2299, 3287, 5709, 
   6897, 9861, 17127, 20691, 20933, 29583, 36157, 62799, 
   108471, 188397, 325413, 397727, 1193181, 3579543

35795441, 2, 4, 8, 447443, 894886, 1789772, 3579544

35795451, 5, 715909, 3579545

35795461, 2, 3, 6, 41, 82, 123, 246, 14551, 29102, 43653, 
   87306, 596591, 1193182, 1789773, 3579546

35795471, 3579547

35795481, 2, 4, 7, 14, 28, 49, 98, 196, 343, 686, 1372, 2609, 
   5218, 10436, 18263, 36526, 73052, 127841, 255682, 511364, 
   894887, 1789774, 3579548


So we could choose from the following pairs for calibration:

209 * 17127209 ticks is  58.3 uS calibration time
363 * 9861 363 ticks is 101.4 uS calibration time
519 * 6897 519 ticks is 145.0 uS calibration time
627 * 5709 627 ticks is 175.2 uS calibration time

I would recommend the pair 363 * 9861 which is closest to the
Current 100 uS calibration time.

Another accuracy improvement on the current algorithm is to
Wait for the ACPI timer value to change before capturing the
Initial TSC value, so only whole ticks are counted.  The current 
algorithm could start the beginning, middle, or end of an ACPI 
counter tick.

Here is an updated measurement algorithm.

  //
  // Wait for ACPI timer to start next count
  //
  Ticks = IoRead32 (TimerAddr);
  while (Ticks == IoRead32 (TimerAddr)) {
CpuPause();
  }

  //
  // Immediately capture start TSC value
  //
  StartTSC = AsmReadTsc (); 

  //
  // Compute the number of ticks to wait to measure TSC frequency.
  // Use 363 * 9861 = 3579543 Hz which is within 2 Hz of 
  // ACPI_TIMER_FREQUENCY.  363 counts is a calibration time of 
  // 101.4 uS.
  // Subtract 1 because the calibration loop waits one extra count.
  //
  Ticks = IoRead32 (TimerAddr) + 363 - 1;

  //
  // Wait until the ACPI timer has counted the number of calibration ticks.
  // Timer wrap-arounds are handled correctly by this function.
  // When the current ACPI timer value is greater than 'Ticks', 
  // the while loop will exit.
  //
  while (((Ticks - IoRead32 (TimerAddr)) & BIT23) == 0) {
CpuPause();
  }

  //
  // Immediately capture end TSC value
  //
  EndTSC = AsmReadTsc ();   // TSC 
value 363 ticks later

  TscFrequency = MultU64x32 (
   (EndTSC - StartTSC), // Total 
number of TSC counts
   9861
   );

We would have to run some experiments to see if this further improves the 
accuracy and consistency of the measurements.

Mike

> -Original Message-
> From: Paolo Bonzini [mailto:paolo.bonz...@gmail.com] On Behalf Of Paolo 
> Bonzini
> Sent: Friday, August 12, 2016 1:31 AM
> To: Zeng, Star <star.z...@intel.com>; edk2-devel@lists.01.org
> Cc: Kinney, Michael D <michael.d.kin...@intel.com>; Gao, Liming
> <liming@intel.com>
> Subject: Re: [edk2] [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC
> Frequency
> 
> 
> 
> On 11/08/2016 04:37, Star Zeng wrote:
> > Minimize the code overhead between the two TSC reads by adding
> > new internal API to calculate TSC Frequency instead of reusing
> > MicroSecondDelay ().
> >
> > Cc: Michael D Kinney <michael.d.kin...@intel.com>
> > Cc: Liming Gao <liming@intel.com>
> > Cc: Paul A Lohr <paul.a.l...@intel.com>
> > Contributed-under: TianoCore Contribution Agreement 1.0
> > Signed-off-by: Star Zeng <star.z...@intel.com>
> > ---
> >  PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c | 56 
> > +-
> >  .../Library/AcpiTimerLib/BaseAcpiTimerLib.c| 33 -
> >  .../Library/AcpiTimerLib/DxeAcpiTimerLib.c | 31 
> >  3 files changed, 99 insertions(+), 21 deletions(-)
> >
> > diff --git a/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
> b/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
> > index 806a4f7ce24c..e6fea231123d 100644
> > --- a/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
> > +++ b/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
> > @@ -1,7 +1,7 @@
> >  /** @file
> >ACPI Timer implements one instance of Timer Library.
> >
> > -  Copyright (c) 2013 - 2015, Intel Corporation

Re: [edk2] [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC Frequency

2016-08-12 Thread Zeng, Star


On 2016/8/12 16:31, Paolo Bonzini wrote:



On 11/08/2016 04:37, Star Zeng wrote:

Minimize the code overhead between the two TSC reads by adding
new internal API to calculate TSC Frequency instead of reusing
MicroSecondDelay ().

Cc: Michael D Kinney 
Cc: Liming Gao 
Cc: Paul A Lohr 
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng 
---
 PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c | 56 +-
 .../Library/AcpiTimerLib/BaseAcpiTimerLib.c| 33 -
 .../Library/AcpiTimerLib/DxeAcpiTimerLib.c | 31 
 3 files changed, 99 insertions(+), 21 deletions(-)

diff --git a/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c 
b/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
index 806a4f7ce24c..e6fea231123d 100644
--- a/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
+++ b/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
@@ -1,7 +1,7 @@
 /** @file
   ACPI Timer implements one instance of Timer Library.

-  Copyright (c) 2013 - 2015, Intel Corporation. All rights reserved.
+  Copyright (c) 2013 - 2016, Intel Corporation. All rights reserved.
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD 
License
   which accompanies this distribution.  The full text of the license may be 
found at
@@ -335,3 +335,57 @@ GetTimeInNanoSecond (

   return NanoSeconds;
 }
+
+/**
+  Calculate TSC frequency.
+
+  The TSC counting frequency is determined by comparing how far it counts
+  during a 100us period as determined by the ACPI timer. The ACPI timer is
+  used because it counts at a known frequency.
+  The TSC is sampled, followed by waiting for ACPI_TIMER_FREQUENCY / 1
+  clocks of the ACPI timer, or 100us. The TSC is then sampled again. The
+  difference multiplied by 1 is the TSC frequency. There will be a small
+  error because of the overhead of reading the ACPI timer. An attempt is
+  made to determine and compensate for this error.
+
+  @return The number of TSC counts per second.
+
+**/
+UINT64
+InternalCalculateTscFrequency (
+  VOID
+  )
+{
+  UINT64  StartTSC;
+  UINT64  EndTSC;
+  UINT16  TimerAddr;
+  UINT32  Ticks;
+  UINT64  TscFrequency;
+  BOOLEAN InterruptState;
+
+  InterruptState = SaveAndDisableInterrupts ();
+
+  TimerAddr = InternalAcpiGetAcpiTimerIoPort ();
+  Ticks = IoRead32 (TimerAddr) + (ACPI_TIMER_FREQUENCY / 1);// Set 
Ticks to 100us in the future


ACPI_TIMER_FREQUENCY is 3579545, thus you're waiting 357 ticks but the
actual result of the division is much closer to 358.  The error is only
0.26%, but it's so simple to reduce it that I think it's worth it.  Just
change (ACPI_TIMER_FREQUENCY / 1) to (ACPI_TIMER_FREQUENCY + 5000) /
1.


Paolo,
It is nice to have it I think, and I prefer to use (ACPI_TIMER_FREQUENCY 
+ 5000) / 1.
Since I have pushed this patch, do you mind to contribute the proposal 
with a new patch?


Thanks,
Star



Another possibility is to count 343 ticks and multiply by 10436; 343 *
10436 is almost exactly ACPI_TIMER_FREQUENCY.

Paolo


+  StartTSC = AsmReadTsc (); // Get 
base value for the TSC
+  //
+  // Wait until the ACPI timer has counted 100us.
+  // Timer wrap-arounds are handled correctly by this function.
+  // When the current ACPI timer value is greater than 'Ticks', the while loop 
will exit.
+  //
+  while (((Ticks - IoRead32 (TimerAddr)) & BIT23) == 0) {
+CpuPause();
+  }
+  EndTSC = AsmReadTsc ();   // TSC 
value 100us later
+
+  TscFrequency = MultU64x32 (
+   (EndTSC - StartTSC), // Number 
of TSC counts in 100us
+   1// Number 
of 100us in a second
+   );
+
+  SetInterruptState (InterruptState);
+
+  return TscFrequency;
+}
+
diff --git a/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c 
b/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c
index 21fdb79908b8..8819ebcfccef 100644
--- a/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c
+++ b/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c
@@ -1,7 +1,7 @@
 /** @file
   ACPI Timer implements one instance of Timer Library.

-  Copyright (c) 2013 - 2014, Intel Corporation. All rights reserved.
+  Copyright (c) 2013 - 2016, Intel Corporation. All rights reserved.
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD 
License
   which accompanies this distribution.  The full text of the license may be 
found at
@@ -17,6 +17,26 @@
 #include 

 /**
+  Calculate TSC frequency.
+
+  The TSC counting frequency is determined by comparing how far it counts
+  during a 100us period as determined by the ACPI timer. The ACPI

Re: [edk2] [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC Frequency

2016-08-12 Thread Paolo Bonzini



On 11/08/2016 04:37, Star Zeng wrote:
> Minimize the code overhead between the two TSC reads by adding
> new internal API to calculate TSC Frequency instead of reusing
> MicroSecondDelay ().
> 
> Cc: Michael D Kinney 
> Cc: Liming Gao 
> Cc: Paul A Lohr 
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Star Zeng 
> ---
>  PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c | 56 
> +-
>  .../Library/AcpiTimerLib/BaseAcpiTimerLib.c| 33 -
>  .../Library/AcpiTimerLib/DxeAcpiTimerLib.c | 31 
>  3 files changed, 99 insertions(+), 21 deletions(-)
> 
> diff --git a/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c 
> b/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
> index 806a4f7ce24c..e6fea231123d 100644
> --- a/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
> +++ b/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
> @@ -1,7 +1,7 @@
>  /** @file
>ACPI Timer implements one instance of Timer Library.
>  
> -  Copyright (c) 2013 - 2015, Intel Corporation. All rights reserved.
> +  Copyright (c) 2013 - 2016, Intel Corporation. All rights reserved.
>This program and the accompanying materials
>are licensed and made available under the terms and conditions of the BSD 
> License
>which accompanies this distribution.  The full text of the license may be 
> found at
> @@ -335,3 +335,57 @@ GetTimeInNanoSecond (
>  
>return NanoSeconds;
>  }
> +
> +/**
> +  Calculate TSC frequency.
> +
> +  The TSC counting frequency is determined by comparing how far it counts
> +  during a 100us period as determined by the ACPI timer. The ACPI timer is
> +  used because it counts at a known frequency.
> +  The TSC is sampled, followed by waiting for ACPI_TIMER_FREQUENCY / 1
> +  clocks of the ACPI timer, or 100us. The TSC is then sampled again. The
> +  difference multiplied by 1 is the TSC frequency. There will be a small
> +  error because of the overhead of reading the ACPI timer. An attempt is
> +  made to determine and compensate for this error.
> +
> +  @return The number of TSC counts per second.
> +
> +**/
> +UINT64
> +InternalCalculateTscFrequency (
> +  VOID
> +  )
> +{
> +  UINT64  StartTSC;
> +  UINT64  EndTSC;
> +  UINT16  TimerAddr;
> +  UINT32  Ticks;
> +  UINT64  TscFrequency;
> +  BOOLEAN InterruptState;
> +
> +  InterruptState = SaveAndDisableInterrupts ();
> +
> +  TimerAddr = InternalAcpiGetAcpiTimerIoPort ();
> +  Ticks = IoRead32 (TimerAddr) + (ACPI_TIMER_FREQUENCY / 1);// Set 
> Ticks to 100us in the future

ACPI_TIMER_FREQUENCY is 3579545, thus you're waiting 357 ticks but the
actual result of the division is much closer to 358.  The error is only
0.26%, but it's so simple to reduce it that I think it's worth it.  Just
change (ACPI_TIMER_FREQUENCY / 1) to (ACPI_TIMER_FREQUENCY + 5000) /
1.

Another possibility is to count 343 ticks and multiply by 10436; 343 *
10436 is almost exactly ACPI_TIMER_FREQUENCY.

Paolo

> +  StartTSC = AsmReadTsc (); // Get 
> base value for the TSC
> +  //
> +  // Wait until the ACPI timer has counted 100us.
> +  // Timer wrap-arounds are handled correctly by this function.
> +  // When the current ACPI timer value is greater than 'Ticks', the while 
> loop will exit.
> +  //
> +  while (((Ticks - IoRead32 (TimerAddr)) & BIT23) == 0) {
> +CpuPause();
> +  }
> +  EndTSC = AsmReadTsc ();   // TSC 
> value 100us later
> +
> +  TscFrequency = MultU64x32 (
> +   (EndTSC - StartTSC), // 
> Number of TSC counts in 100us
> +   1// 
> Number of 100us in a second
> +   );
> +
> +  SetInterruptState (InterruptState);
> +
> +  return TscFrequency;
> +}
> +
> diff --git a/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c 
> b/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c
> index 21fdb79908b8..8819ebcfccef 100644
> --- a/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c
> +++ b/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c
> @@ -1,7 +1,7 @@
>  /** @file
>ACPI Timer implements one instance of Timer Library.
>  
> -  Copyright (c) 2013 - 2014, Intel Corporation. All rights reserved.
> +  Copyright (c) 2013 - 2016, Intel Corporation. All rights reserved.
>This program and the accompanying materials
>are licensed and made available under the terms and conditions of the BSD 
> License
>which accompanies this distribution.  The full text of the license may be 
> found at
> @@ -17,6 +17,26 @@
>  #include 
>  
>  /**
> +  Calculate TSC frequency.
> +
> +  The TSC counting frequency is determined by comparing how far it counts
> +  during a 100us period as determined by the ACPI timer. The ACPI timer is
> +

Re: [edk2] [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC Frequency

2016-08-11 Thread Zeng, Star


On 2016/8/11 21:41, Brian J. Johnson wrote:

On 08/10/2016 09:37 PM, Star Zeng wrote:

Minimize the code overhead between the two TSC reads by adding
new internal API to calculate TSC Frequency instead of reusing
MicroSecondDelay ().


Why not just use the MSR_PLATFORM_INFO (0xce) register bits 15..8, on
CPUs where it's available, to read the TSC frequency directly?


Per my understanding, not every generation CPU has this 
MSR_PLATFORM_INFO (0xce) register defined, and also MSR_PLATFORM_INFO 
(0xce) register bits 15..8 is just the ratio, then the radio needs to 
multiply external clock frequency which may be different for various 
generation CPU.
I believe the library's position stands as a generic library and not for 
specific CPU.



Thanks,
Star
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Re: [edk2] [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC Frequency

2016-08-11 Thread Brian J. Johnson


On 08/10/2016 09:37 PM, Star Zeng wrote:

Minimize the code overhead between the two TSC reads by adding
new internal API to calculate TSC Frequency instead of reusing
MicroSecondDelay ().


Why not just use the MSR_PLATFORM_INFO (0xce) register bits 15..8, on 
CPUs where it's available, to read the TSC frequency directly?

--

Brian J. Johnson



  My statements are my own, are not authorized by SGI, and do not
  necessarily represent SGI’s positions.
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Re: [edk2] [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC Frequency

2016-08-10 Thread Kinney, Michael D

Reviewed-by: : Michael D Kinney 

> -Original Message-
> From: Zeng, Star
> Sent: Wednesday, August 10, 2016 7:38 PM
> To: edk2-devel@lists.01.org
> Cc: Zeng, Star ; Kinney, Michael D 
> ;
> Gao, Liming ; Lohr, Paul A 
> Subject: [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC Frequency
> 
> Minimize the code overhead between the two TSC reads by adding
> new internal API to calculate TSC Frequency instead of reusing
> MicroSecondDelay ().
> 
> Cc: Michael D Kinney 
> Cc: Liming Gao 
> Cc: Paul A Lohr 
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Star Zeng 
> ---
>  PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c | 56 
> +-
>  .../Library/AcpiTimerLib/BaseAcpiTimerLib.c| 33 -
>  .../Library/AcpiTimerLib/DxeAcpiTimerLib.c | 31 
>  3 files changed, 99 insertions(+), 21 deletions(-)
> 
> diff --git a/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
> b/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
> index 806a4f7ce24c..e6fea231123d 100644
> --- a/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
> +++ b/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
> @@ -1,7 +1,7 @@
>  /** @file
>ACPI Timer implements one instance of Timer Library.
> 
> -  Copyright (c) 2013 - 2015, Intel Corporation. All rights reserved.
> +  Copyright (c) 2013 - 2016, Intel Corporation. All rights reserved.
>This program and the accompanying materials
>are licensed and made available under the terms and conditions of the BSD 
> License
>which accompanies this distribution.  The full text of the license may be 
> found at
> @@ -335,3 +335,57 @@ GetTimeInNanoSecond (
> 
>return NanoSeconds;
>  }
> +
> +/**
> +  Calculate TSC frequency.
> +
> +  The TSC counting frequency is determined by comparing how far it counts
> +  during a 100us period as determined by the ACPI timer. The ACPI timer is
> +  used because it counts at a known frequency.
> +  The TSC is sampled, followed by waiting for ACPI_TIMER_FREQUENCY / 1
> +  clocks of the ACPI timer, or 100us. The TSC is then sampled again. The
> +  difference multiplied by 1 is the TSC frequency. There will be a small
> +  error because of the overhead of reading the ACPI timer. An attempt is
> +  made to determine and compensate for this error.
> +
> +  @return The number of TSC counts per second.
> +
> +**/
> +UINT64
> +InternalCalculateTscFrequency (
> +  VOID
> +  )
> +{
> +  UINT64  StartTSC;
> +  UINT64  EndTSC;
> +  UINT16  TimerAddr;
> +  UINT32  Ticks;
> +  UINT64  TscFrequency;
> +  BOOLEAN InterruptState;
> +
> +  InterruptState = SaveAndDisableInterrupts ();
> +
> +  TimerAddr = InternalAcpiGetAcpiTimerIoPort ();
> +  Ticks = IoRead32 (TimerAddr) + (ACPI_TIMER_FREQUENCY / 1);// Set 
> Ticks to
> 100us in the future
> +
> +  StartTSC = AsmReadTsc (); // Get 
> base
> value for the TSC
> +  //
> +  // Wait until the ACPI timer has counted 100us.
> +  // Timer wrap-arounds are handled correctly by this function.
> +  // When the current ACPI timer value is greater than 'Ticks', the while 
> loop will
> exit.
> +  //
> +  while (((Ticks - IoRead32 (TimerAddr)) & BIT23) == 0) {
> +CpuPause();
> +  }
> +  EndTSC = AsmReadTsc ();   // TSC 
> value
> 100us later
> +
> +  TscFrequency = MultU64x32 (
> +   (EndTSC - StartTSC), // 
> Number of TSC
> counts in 100us
> +   1// 
> Number of
> 100us in a second
> +   );
> +
> +  SetInterruptState (InterruptState);
> +
> +  return TscFrequency;
> +}
> +
> diff --git a/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c
> b/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c
> index 21fdb79908b8..8819ebcfccef 100644
> --- a/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c
> +++ b/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c
> @@ -1,7 +1,7 @@
>  /** @file
>ACPI Timer implements one instance of Timer Library.
> 
> -  Copyright (c) 2013 - 2014, Intel Corporation. All rights reserved.
> +  Copyright (c) 2013 - 2016, Intel Corporation. All rights reserved.
>This program and the accompanying materials
>are licensed and made available under the terms and conditions of the BSD 
> License
>which accompanies this distribution.  The full text of the license may be 
> found at
> @@ -17,6 +17,26 @@
>  #include 
> 
>  /**
> +  Calculate TSC frequency.
> +
> +  The TSC counting frequency is determined by comparing how far it counts
> +  during a 100us period as determined by the ACPI timer. The ACPI timer is
> +  used because it

Re: [edk2] [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC Frequency

2016-08-10 Thread Gao, Liming

Reviewed-by: Liming Gao 

> -Original Message-
> From: Zeng, Star
> Sent: Thursday, August 11, 2016 10:38 AM
> To: edk2-devel@lists.01.org
> Cc: Zeng, Star ; Kinney, Michael D
> ; Gao, Liming ; Lohr,
> Paul A 
> Subject: [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC
> Frequency
> 
> Minimize the code overhead between the two TSC reads by adding
> new internal API to calculate TSC Frequency instead of reusing
> MicroSecondDelay ().
> 
> Cc: Michael D Kinney 
> Cc: Liming Gao 
> Cc: Paul A Lohr 
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Star Zeng 
> ---
>  PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c | 56
> +-
>  .../Library/AcpiTimerLib/BaseAcpiTimerLib.c| 33 -
>  .../Library/AcpiTimerLib/DxeAcpiTimerLib.c | 31 
>  3 files changed, 99 insertions(+), 21 deletions(-)
> 
> diff --git a/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
> b/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
> index 806a4f7ce24c..e6fea231123d 100644
> --- a/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
> +++ b/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
> @@ -1,7 +1,7 @@
>  /** @file
>ACPI Timer implements one instance of Timer Library.
> 
> -  Copyright (c) 2013 - 2015, Intel Corporation. All rights reserved.
> +  Copyright (c) 2013 - 2016, Intel Corporation. All rights reserved.
>This program and the accompanying materials
>are licensed and made available under the terms and conditions of the BSD
> License
>which accompanies this distribution.  The full text of the license may be
> found at
> @@ -335,3 +335,57 @@ GetTimeInNanoSecond (
> 
>return NanoSeconds;
>  }
> +
> +/**
> +  Calculate TSC frequency.
> +
> +  The TSC counting frequency is determined by comparing how far it counts
> +  during a 100us period as determined by the ACPI timer. The ACPI timer is
> +  used because it counts at a known frequency.
> +  The TSC is sampled, followed by waiting for ACPI_TIMER_FREQUENCY /
> 1
> +  clocks of the ACPI timer, or 100us. The TSC is then sampled again. The
> +  difference multiplied by 1 is the TSC frequency. There will be a small
> +  error because of the overhead of reading the ACPI timer. An attempt is
> +  made to determine and compensate for this error.
> +
> +  @return The number of TSC counts per second.
> +
> +**/
> +UINT64
> +InternalCalculateTscFrequency (
> +  VOID
> +  )
> +{
> +  UINT64  StartTSC;
> +  UINT64  EndTSC;
> +  UINT16  TimerAddr;
> +  UINT32  Ticks;
> +  UINT64  TscFrequency;
> +  BOOLEAN InterruptState;
> +
> +  InterruptState = SaveAndDisableInterrupts ();
> +
> +  TimerAddr = InternalAcpiGetAcpiTimerIoPort ();
> +  Ticks = IoRead32 (TimerAddr) + (ACPI_TIMER_FREQUENCY / 1);//
> Set Ticks to 100us in the future
> +
> +  StartTSC = AsmReadTsc (); // Get 
> base value for the
> TSC
> +  //
> +  // Wait until the ACPI timer has counted 100us.
> +  // Timer wrap-arounds are handled correctly by this function.
> +  // When the current ACPI timer value is greater than 'Ticks', the while 
> loop
> will exit.
> +  //
> +  while (((Ticks - IoRead32 (TimerAddr)) & BIT23) == 0) {
> +CpuPause();
> +  }
> +  EndTSC = AsmReadTsc ();   // TSC 
> value 100us later
> +
> +  TscFrequency = MultU64x32 (
> +   (EndTSC - StartTSC), // 
> Number of TSC counts in
> 100us
> +   1// 
> Number of 100us in a second
> +   );
> +
> +  SetInterruptState (InterruptState);
> +
> +  return TscFrequency;
> +}
> +
> diff --git a/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c
> b/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c
> index 21fdb79908b8..8819ebcfccef 100644
> --- a/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c
> +++ b/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c
> @@ -1,7 +1,7 @@
>  /** @file
>ACPI Timer implements one instance of Timer Library.
> 
> -  Copyright (c) 2013 - 2014, Intel Corporation. All rights reserved.
> +  Copyright (c) 2013 - 2016, Intel Corporation. All rights reserved.
>This program and the accompanying materials
>are licensed and made available under the terms and conditions of the BSD
> License
>which accompanies this distribution.  The full text of the license may be
> found at
> @@ -17,6 +17,26 @@
>  #include 
> 
>  /**
> +  Calculate TSC frequency.
> +
> +  The TSC counting frequency is determined by comparing how far it counts
> +  during a 100us period as determined by the ACPI timer. The ACPI timer is
> +  used because it counts at a known

[edk2] [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC Frequency

2016-08-10 Thread Star Zeng

Minimize the code overhead between the two TSC reads by adding
new internal API to calculate TSC Frequency instead of reusing
MicroSecondDelay ().

Cc: Michael D Kinney 
Cc: Liming Gao 
Cc: Paul A Lohr 
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng 
---
 PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c | 56 +-
 .../Library/AcpiTimerLib/BaseAcpiTimerLib.c| 33 -
 .../Library/AcpiTimerLib/DxeAcpiTimerLib.c | 31 
 3 files changed, 99 insertions(+), 21 deletions(-)

diff --git a/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c 
b/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
index 806a4f7ce24c..e6fea231123d 100644
--- a/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
+++ b/PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
@@ -1,7 +1,7 @@
 /** @file
   ACPI Timer implements one instance of Timer Library.
 
-  Copyright (c) 2013 - 2015, Intel Corporation. All rights reserved.
+  Copyright (c) 2013 - 2016, Intel Corporation. All rights reserved.
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD 
License
   which accompanies this distribution.  The full text of the license may be 
found at
@@ -335,3 +335,57 @@ GetTimeInNanoSecond (
 
   return NanoSeconds;
 }
+
+/**
+  Calculate TSC frequency.
+
+  The TSC counting frequency is determined by comparing how far it counts
+  during a 100us period as determined by the ACPI timer. The ACPI timer is
+  used because it counts at a known frequency.
+  The TSC is sampled, followed by waiting for ACPI_TIMER_FREQUENCY / 1
+  clocks of the ACPI timer, or 100us. The TSC is then sampled again. The
+  difference multiplied by 1 is the TSC frequency. There will be a small
+  error because of the overhead of reading the ACPI timer. An attempt is
+  made to determine and compensate for this error.
+
+  @return The number of TSC counts per second.
+
+**/
+UINT64
+InternalCalculateTscFrequency (
+  VOID
+  )
+{
+  UINT64  StartTSC;
+  UINT64  EndTSC;
+  UINT16  TimerAddr;
+  UINT32  Ticks;
+  UINT64  TscFrequency;
+  BOOLEAN InterruptState;
+
+  InterruptState = SaveAndDisableInterrupts ();
+
+  TimerAddr = InternalAcpiGetAcpiTimerIoPort ();
+  Ticks = IoRead32 (TimerAddr) + (ACPI_TIMER_FREQUENCY / 1);// Set 
Ticks to 100us in the future
+
+  StartTSC = AsmReadTsc (); // Get 
base value for the TSC
+  //
+  // Wait until the ACPI timer has counted 100us.
+  // Timer wrap-arounds are handled correctly by this function.
+  // When the current ACPI timer value is greater than 'Ticks', the while loop 
will exit.
+  //
+  while (((Ticks - IoRead32 (TimerAddr)) & BIT23) == 0) {
+CpuPause();
+  }
+  EndTSC = AsmReadTsc ();   // TSC 
value 100us later
+
+  TscFrequency = MultU64x32 (
+   (EndTSC - StartTSC), // Number 
of TSC counts in 100us
+   1// Number 
of 100us in a second
+   );
+
+  SetInterruptState (InterruptState);
+
+  return TscFrequency;
+}
+
diff --git a/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c 
b/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c
index 21fdb79908b8..8819ebcfccef 100644
--- a/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c
+++ b/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c
@@ -1,7 +1,7 @@
 /** @file
   ACPI Timer implements one instance of Timer Library.
 
-  Copyright (c) 2013 - 2014, Intel Corporation. All rights reserved.
+  Copyright (c) 2013 - 2016, Intel Corporation. All rights reserved.
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD 
License
   which accompanies this distribution.  The full text of the license may be 
found at
@@ -17,6 +17,26 @@
 #include 
 
 /**
+  Calculate TSC frequency.
+
+  The TSC counting frequency is determined by comparing how far it counts
+  during a 100us period as determined by the ACPI timer. The ACPI timer is
+  used because it counts at a known frequency.
+  The TSC is sampled, followed by waiting for ACPI_TIMER_FREQUENCY / 1
+  clocks of the ACPI timer, or 100us. The TSC is then sampled again. The
+  difference multiplied by 1 is the TSC frequency. There will be a small
+  error because of the overhead of reading the ACPI timer. An attempt is
+  made to determine and compensate for this error.
+
+  @return The number of TSC counts per second.
+
+**/
+UINT64
+InternalCalculateTscFrequency (
+  VOID
+  );
+
+/**
   Internal function to retrieves the 64-bit frequency in Hz.
 
   Internal function to retrieves the 64-bit frequency in Hz.
@@ -29,14 +49,5 @@

Re: [edk2] [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC Frequency

Re: [edk2] [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC Frequency

Re: [edk2] [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC Frequency

Re: [edk2] [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC Frequency

Re: [edk2] [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC Frequency

Re: [edk2] [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC Frequency

Re: [edk2] [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC Frequency

[edk2] [PATCH] PcAtChipsetPkg AcpiTimerLib: Get more accurate TSC Frequency

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