Re: [ros-dev] [ros-diffs] [tkreuzer] 53695: [HAL] Implement lazy irql for APIC. This is useful for VMs, since APIC usually has high overhead due to the need of invoking the hypervisor on every irql raise and lower. With laz...

[Alex Ionescu]

http://blogs.technet.com/b/askperf/archive/2010/07/23/windows-xp-guests-exh…

Windows does have APIC Lazy IRQL, Microsoft are not idiots.

Best regards,
Alex Ionescu


On Mon, Sep 12, 2011 at 2:46 AM, <tkreuzer(a)svn.reactos.org> wrote:

>   Author: tkreuzer
>  Date: Mon Sep 12 09:46:20 2011
>  New Revision: 53695
>
>  URL: http://svn.reactos.org/svn/reactos?rev=53695&view=rev
>  Log:
>  [HAL]
>  Implement lazy irql for APIC. This is useful for VMs, since APIC usually
>  has high overhead due to the need of invoking the hypervisor on every irql
>  raise and lower. With lazy irql we avoid that until absolutely neccessary.
>  Note that we misuse the PCR's IRR field to save the current hardware irql.
>  Its a huge performance boost (some parts take half the time), making APIC
>  performance close to PIC performance on VBox. This is something that Windows
>  doesn't have :)
>
>  Modified:
>     trunk/reactos/hal/halx86/apic/apic.c
>     trunk/reactos/hal/halx86/apic/rtctimer.c
>
>  Modified: trunk/reactos/hal/halx86/apic/apic.c
>  URL:
>
> http://svn.reactos.org/svn/reactos/trunk/reactos/hal/halx86/apic/apic.c?rev…
>
>  ==============================================================================
>  --- trunk/reactos/hal/halx86/apic/apic.c [iso-8859-1] (original)
>  +++ trunk/reactos/hal/halx86/apic/apic.c [iso-8859-1] Mon Sep 12 09:46:20
>  2011
>  @@ -17,6 +17,8 @@
>
>   #include "apic.h"
>   void HackEoi(void);
>  +
>  +#define APIC_LAZY_IRQL
>
>   /* GLOBALS
>  ********************************************************************/
>
>  @@ -105,6 +107,46 @@
>
>   VOID
>   FORCEINLINE
>  +ApicWriteIORedirectionEntry(
>  +    UCHAR Index,
>  +    IOAPIC_REDIRECTION_REGISTER ReDirReg)
>  +{
>  +    IOApicWrite(IOAPIC_REDTBL + 2 * Index, ReDirReg.Long0);
>  +    IOApicWrite(IOAPIC_REDTBL + 2 * Index + 1, ReDirReg.Long1);
>  +}
>  +
>  +IOAPIC_REDIRECTION_REGISTER
>  +FORCEINLINE
>  +ApicReadIORedirectionEntry(
>  +    UCHAR Index)
>  +{
>  +    IOAPIC_REDIRECTION_REGISTER ReDirReg;
>  +
>  +    ReDirReg.Long0 = IOApicRead(IOAPIC_REDTBL + 2 * Index);
>  +    ReDirReg.Long1 = IOApicRead(IOAPIC_REDTBL + 2 * Index + 1);
>  +
>  +    return ReDirReg;
>  +}
>  +
>  +VOID
>  +FORCEINLINE
>  +ApicRequestInterrupt(IN UCHAR Vector)
>  +{
>  +    APIC_COMMAND_REGISTER CommandRegister;
>  +
>  +    /* Setup the command register */
>  +    CommandRegister.Long0 = 0;
>  +    CommandRegister.Vector = Vector;
>  +    CommandRegister.MessageType = APIC_MT_Fixed;
>  +    CommandRegister.TriggerMode = APIC_TGM_Edge;
>  +    CommandRegister.DestinationShortHand = APIC_DSH_Self;
>  +
>  +    /* Write the low dword to send the interrupt */
>  +    ApicWrite(APIC_ICR0, CommandRegister.Long0);
>  +}
>  +
>  +VOID
>  +FORCEINLINE
>   ApicSendEOI(void)
>   {
>      //ApicWrite(APIC_EOI, 0);
>  @@ -125,6 +167,12 @@
>   {
>   #ifdef _M_AMD64
>      return (KIRQL)__readcr8();
>  +#elif defined(APIC_LAZY_IRQL)
>  +    // HACK: some magic to Sync VBox's APIC registers
>  +    ApicRead(APIC_VER);
>  +
>  +    /* Return the field in the PCR */
>  +    return (KIRQL)__readfsbyte(FIELD_OFFSET(KPCR, Irql));
>   #else
>      // HACK: some magic to Sync VBox's APIC registers
>      ApicRead(APIC_VER);
>  @@ -136,16 +184,42 @@
>
>   VOID
>   FORCEINLINE
>  -ApicSetCurrentIrql(KIRQL Irql)
>  +ApicRaiseIrql(KIRQL Irql)
>   {
>   #ifdef _M_AMD64
>      __writecr8(Irql);
>  +#elif defined(APIC_LAZY_IRQL)
>  +    __writefsbyte(FIELD_OFFSET(KPCR, Irql), Irql);
>   #else
>      /* Convert IRQL and write the TPR */
>      ApicWrite(APIC_TPR, IrqlToTpr(Irql));
>   #endif
>   }
>
>  +VOID
>  +FORCEINLINE
>  +ApicLowerIrql(KIRQL Irql)
>  +{
>  +#ifdef _M_AMD64
>  +    __writecr8(Irql);
>  +#elif defined(APIC_LAZY_IRQL)
>  +    __writefsbyte(FIELD_OFFSET(KPCR, Irql), Irql);
>  +
>  +    /* Is the new Irql lower than set in the TPR? */
>  +    if (Irql < KeGetPcr()->IRR)
>  +    {
>  +        /* Save the new hard IRQL in the IRR field */
>  +        KeGetPcr()->IRR = Irql;
>  +
>  +        /* Need to lower it back */
>  +        ApicWrite(APIC_TPR, IrqlToTpr(Irql));
>  +    }
>  +#else
>  +    /* Convert IRQL and write the TPR */
>  +    ApicWrite(APIC_TPR, IrqlToTpr(Irql));
>  +#endif
>  +}
>  +
>   UCHAR
>   FASTCALL
>   HalpIrqToVector(UCHAR Irq)
>  @@ -171,6 +245,13 @@
>   HalpVectorToIrq(UCHAR Vector)
>   {
>      return HalpVectorToIndex[Vector];
>  +}
>  +
>  +VOID
>  +NTAPI
>  +HalpSendEOI(VOID)
>  +{
>  +    ApicSendEOI();
>   }
>
>   VOID
>  @@ -311,31 +392,10 @@
>      ApicWrite(APIC_ERRLVTR, LvtEntry.Long);
>
>      /* Set the IRQL from the PCR */
>  -    ApicSetCurrentIrql(KeGetPcr()->Irql);
>  -}
>  -
>  -
>  -VOID
>  -FORCEINLINE
>  -ApicWriteIORedirectionEntry(
>  -    UCHAR Index,
>  -    IOAPIC_REDIRECTION_REGISTER ReDirReg)
>  -{
>  -    IOApicWrite(IOAPIC_REDTBL + 2 * Index, ReDirReg.Long0);
>  -    IOApicWrite(IOAPIC_REDTBL + 2 * Index + 1, ReDirReg.Long1);
>  -}
>  -
>  -IOAPIC_REDIRECTION_REGISTER
>  -FORCEINLINE
>  -ApicReadIORedirectionEntry(
>  -    UCHAR Index)
>  -{
>  -    IOAPIC_REDIRECTION_REGISTER ReDirReg;
>  -
>  -    ReDirReg.Long0 = IOApicRead(IOAPIC_REDTBL + 2 * Index);
>  -    ReDirReg.Long1 = IOApicRead(IOAPIC_REDTBL + 2 * Index + 1);
>  -
>  -    return ReDirReg;
>  +    ApicWrite(APIC_TPR, IrqlToTpr(KeGetPcr()->Irql));
>  +
>  +    /* Save the new hard IRQL in the IRR field */
>  +    KeGetPcr()->IRR = KeGetPcr()->Irql;
>   }
>
>   UCHAR
>  @@ -486,6 +546,9 @@
>      __writeeflags(EFlags);
>   }
>
>  +
>  +/* SOFTWARE INTERRUPT TRAPS
>  ***************************************************/
>  +
>   VOID
>   DECLSPEC_NORETURN
>   FASTCALL
>  @@ -493,17 +556,25 @@
>   {
>      KPROCESSOR_MODE ProcessorMode;
>      KIRQL OldIrql;
>  -    ASSERT(ApicGetCurrentIrql() < APC_LEVEL);
>      ASSERT(ApicGetProcessorIrql() == APC_LEVEL);
>
>     /* Enter trap */
>      KiEnterInterruptTrap(TrapFrame);
>
>  +#ifdef APIC_LAZY_IRQL
>  +    if (!HalBeginSystemInterrupt(APC_LEVEL, APC_VECTOR, &OldIrql))
>  +    {
>  +        /* "Spurious" interrupt, exit the interrupt */
>  +        KiEoiHelper(TrapFrame);
>  +    }
>  +#else
>      /* Save the old IRQL */
>      OldIrql = ApicGetCurrentIrql();
>  +    ASSERT(OldIrql < APC_LEVEL);
>  +#endif
>
>      /* Raise to APC_LEVEL */
>  -    ApicSetCurrentIrql(APC_LEVEL);
>  +    ApicRaiseIrql(APC_LEVEL);
>
>      /* End the interrupt */
>      ApicSendEOI();
>  @@ -521,7 +592,7 @@
>      _disable();
>
>      /* Restore the old IRQL */
>  -    ApicSetCurrentIrql(OldIrql);
>  +    ApicLowerIrql(OldIrql);
>
>      /* Exit the interrupt */
>      KiEoiHelper(TrapFrame);
>  @@ -534,17 +605,25 @@
>   HalpDispatchInterruptHandler(IN PKTRAP_FRAME TrapFrame)
>   {
>      KIRQL OldIrql;
>  -    ASSERT(ApicGetCurrentIrql() < DISPATCH_LEVEL);
>      ASSERT(ApicGetProcessorIrql() == DISPATCH_LEVEL);
>
>     /* Enter trap */
>      KiEnterInterruptTrap(TrapFrame);
>
>  -    /* Save the old IRQL */
>  +#ifdef APIC_LAZY_IRQL
>  +    if (!HalBeginSystemInterrupt(DISPATCH_LEVEL, DISPATCH_VECTOR,
>  &OldIrql))
>  +    {
>  +        /* "Spurious" interrupt, exit the interrupt */
>  +        KiEoiHelper(TrapFrame);
>  +    }
>  +#else
>  +    /* Get the current IRQL */
>      OldIrql = ApicGetCurrentIrql();
>  +    ASSERT(OldIrql < DISPATCH_LEVEL);
>  +#endif
>
>      /* Raise to DISPATCH_LEVEL */
>  -    ApicSetCurrentIrql(DISPATCH_LEVEL);
>  +    ApicRaiseIrql(DISPATCH_LEVEL);
>
>      /* End the interrupt */
>      ApicSendEOI();
>  @@ -555,37 +634,23 @@
>      _disable();
>
>      /* Restore the old IRQL */
>  -    ApicSetCurrentIrql(OldIrql);
>  +    ApicLowerIrql(OldIrql);
>
>      /* Exit the interrupt */
>      KiEoiHelper(TrapFrame);
>   }
>   #endif
>
>  -VOID
>  -NTAPI
>  -HalpSendEOI(VOID)
>  -{
>  -    ApicSendEOI();
>  -}
>  -
>  -/* PUBLIC FUNCTIONS
>  ***********************************************************/
>  +
>  +/* SOFTWARE INTERRUPTS
>  ********************************************************/
>  +
>
>   VOID
>   FASTCALL
>   HalRequestSoftwareInterrupt(IN KIRQL Irql)
>   {
>  -    APIC_COMMAND_REGISTER CommandRegister;
>  -
>  -    /* Setup the command register */
>  -    CommandRegister.Long0 = 0;
>  -    CommandRegister.Vector = IrqlToTpr(Irql);
>  -    CommandRegister.MessageType = APIC_MT_Fixed;
>  -    CommandRegister.TriggerMode = APIC_TGM_Edge;
>  -    CommandRegister.DestinationShortHand = APIC_DSH_Self;
>  -
>  -    /* Write the low dword to send the interrupt */
>  -    ApicWrite(APIC_ICR0, CommandRegister.Long0);
>  +    /* Convert irql to vector and request an interrupt */
>  +    ApicRequestInterrupt(IrqlToTpr(Irql));
>   }
>
>   VOID
>  @@ -595,6 +660,9 @@
>   {
>      /* Nothing to do */
>   }
>  +
>  +
>  +/* SYSTEM INTERRUPTS
>  **********************************************************/
>
>   BOOLEAN
>   NTAPI
>  @@ -678,11 +746,37 @@
>      IN UCHAR Vector,
>      OUT PKIRQL OldIrql)
>   {
>  +    KIRQL CurrentIrql;
>  +
>      /* Get the current IRQL */
>  -    *OldIrql = ApicGetCurrentIrql();
>  +    CurrentIrql = ApicGetCurrentIrql();
>  +
>  +#ifdef APIC_LAZY_IRQL
>  +    /* Check if this interrupt is allowed */
>  +    if (CurrentIrql >= Irql)
>  +    {
>  +        /* It is not, set the real Irql in the TPR! */
>  +        ApicWrite(APIC_TPR, IrqlToTpr(CurrentIrql));
>  +
>  +        /* Save the new hard IRQL in the IRR field */
>  +        KeGetPcr()->IRR = CurrentIrql;
>  +
>  +        /* End this interrupt */
>  +        ApicSendEOI();
>  +
>  +        // FIXME: level interrupts
>  +        /* Re-request the interrupt to be handled later */
>  +        ApicRequestInterrupt(Vector);
>  +
>  +        /* Pretend it was a spurious interrupt */
>  +        return FALSE;
>  +    }
>  +#endif
>  +    /* Save the current IRQL */
>  +    *OldIrql = CurrentIrql;
>
>      /* Set the new IRQL */
>  -    ApicSetCurrentIrql(Irql);
>  +    ApicRaiseIrql(Irql);
>
>      /* Turn on interrupts */
>      _enable();
>  @@ -701,9 +795,11 @@
>      ApicSendEOI();
>
>      /* Restore the old IRQL */
>  -    ApicSetCurrentIrql(OldIrql);
>  -}
>  -
>  +    ApicLowerIrql(OldIrql);
>  +}
>  +
>  +
>  +/* IRQL MANAGEMENT
>  ************************************************************/
>
>   KIRQL
>   NTAPI
>  @@ -726,8 +822,8 @@
>          KeBugCheck(IRQL_NOT_LESS_OR_EQUAL);
>      }
>   #endif
>  -    /* Convert the new IRQL to a TPR value and write the register */
>  -    ApicSetCurrentIrql(OldIrql);
>  +    /* Set the new IRQL */
>  +    ApicLowerIrql(OldIrql);
>   }
>
>   KIRQL
>  @@ -748,7 +844,7 @@
>      }
>   #endif
>      /* Convert the new IRQL to a TPR value and write the register */
>  -    ApicSetCurrentIrql(NewIrql);
>  +    ApicRaiseIrql(NewIrql);
>
>      /* Return old IRQL */
>      return OldIrql;
>
>  Modified: trunk/reactos/hal/halx86/apic/rtctimer.c
>  URL:
>
> http://svn.reactos.org/svn/reactos/trunk/reactos/hal/halx86/apic/rtctimer.c…
>
>  ==============================================================================
>  --- trunk/reactos/hal/halx86/apic/rtctimer.c [iso-8859-1] (original)
>  +++ trunk/reactos/hal/halx86/apic/rtctimer.c [iso-8859-1] Mon Sep 12
>  09:46:20 2011
>  @@ -111,7 +111,7 @@
>      KiEnterInterruptTrap(TrapFrame);
>
>      /* Start the interrupt */
>  -    if (HalBeginSystemInterrupt(CLOCK_LEVEL, PRIMARY_VECTOR_BASE, &Irql))
>  +    if (HalBeginSystemInterrupt(CLOCK_LEVEL, HalpClockVector, &Irql))
>      {
>          /* Read register C, so that the next interrupt can happen */
>          HalpReadCmos(RTC_REGISTER_C);;
>
>
>