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Re: [win-pv-devel] [PATCH 6/9] Create a thread per VBD to handle backend change watches

> -----Original Message-----
> From: win-pv-devel [mailto:win-pv-devel-bounces@xxxxxxxxxxxxxxxxxxxx] On
> Behalf Of Owen Smith
> Sent: 22 April 2016 15:16
> To: win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> Cc: Owen Smith
> Subject: [win-pv-devel] [PATCH 6/9] Create a thread per VBD to handle
> backend change watches
> 
> Using a single thread for all backend watch events pust unneccesary
> strain on xenstore when multiple vbds are in use, as each change
> causes XenVbd to check several values in all backend areas.
> 
> Signed-off-by: Owen Smith <owen.smith@xxxxxxxxxx>

Acked-by: Paul Durrant <paul.durrant@xxxxxxxxxx>

> ---
>  src/xenvbd/fdo.c      | 55 
> +--------------------------------------------------
>  src/xenvbd/frontend.c | 54 +++++++++++++++++++++++++++++++++++---
> ------------
>  src/xenvbd/frontend.h |  7 -------
>  src/xenvbd/pdo.c      | 31 ++++++++++-------------------
>  src/xenvbd/pdo.h      |  7 -------
>  5 files changed, 49 insertions(+), 105 deletions(-)
> 
> diff --git a/src/xenvbd/fdo.c b/src/xenvbd/fdo.c
> index dab7ae1..29ec966 100644
> --- a/src/xenvbd/fdo.c
> +++ b/src/xenvbd/fdo.c
> @@ -93,7 +93,6 @@ struct _XENVBD_FDO {
>      PXENVBD_THREAD              ScanThread;
>      KEVENT                      ScanEvent;
>      PXENBUS_STORE_WATCH         ScanWatch;
> -    PXENVBD_THREAD              FrontendThread;
> 
>      // Statistics
>      LONG                        CurrentSrbs;
> @@ -648,7 +647,6 @@ __FdoEnumerate(
>          if (PdoCreate(Fdo,
>                        Device,
>                        TargetId,
> -                      ThreadGetEvent(Fdo->FrontendThread),
>                        DeviceType)) {
>              *NeedInvalidate = TRUE;
>          }
> @@ -712,43 +710,6 @@ FdoScan(
>      return STATUS_SUCCESS;
>  }
> 
> -__checkReturn
> -static DECLSPEC_NOINLINE NTSTATUS
> -FdoFrontend(
> -    __in PXENVBD_THREAD              Thread,
> -    __in PVOID                       Context
> -    )
> -{
> -    PXENVBD_FDO     Fdo = Context;
> -
> -    for (;;) {
> -        ULONG       TargetId;
> -        KIRQL       Irql;
> -
> -        if (!ThreadWait(Thread))
> -            break;
> -
> -        KeAcquireSpinLock(&Fdo->Lock, &Irql);
> -
> -        if (Fdo->DevicePower != PowerDeviceD0) {
> -            KeReleaseSpinLock(&Fdo->Lock, Irql);
> -            continue;
> -        }
> -
> -        for (TargetId = 0; TargetId < XENVBD_MAX_TARGETS; ++TargetId) {
> -            PXENVBD_PDO Pdo = __FdoGetPdo(Fdo, TargetId);
> -            if (Pdo) {
> -                PdoBackendPathChanged(Pdo);
> -                PdoDereference(Pdo);
> -            }
> -        }
> -
> -        KeReleaseSpinLock(&Fdo->Lock, Irql);
> -    }
> -
> -    return STATUS_SUCCESS;
> -}
> -
> 
> //=========================================================
> ====================
>  // Initialize, Start, Stop
> 
> @@ -1556,13 +1517,9 @@ __FdoInitialize(
>      if (!NT_SUCCESS(Status))
>          goto fail3;
> 
> -    Status = ThreadCreate(FdoFrontend, Fdo, &Fdo->FrontendThread);
> -    if (!NT_SUCCESS(Status))
> -        goto fail4;
> -
>      Status = ThreadCreate(FdoDevicePower, Fdo, &Fdo-
> >DevicePowerThread);
>      if (!NT_SUCCESS(Status))
> -        goto fail5;
> +        goto fail4;
> 
>      // query enumerator
>      // fix this up to query from device location(?)
> @@ -1574,11 +1531,6 @@ __FdoInitialize(
>      Trace("<===== (%d)\n", KeGetCurrentIrql());
>      return STATUS_SUCCESS;
> 
> -fail5:
> -    Error("fail5\n");
> -    ThreadAlert(Fdo->FrontendThread);
> -    ThreadJoin(Fdo->FrontendThread);
> -    Fdo->FrontendThread = NULL;
>  fail4:
>      Error("fail4\n");
>      ThreadAlert(Fdo->ScanThread);
> @@ -1621,11 +1573,6 @@ __FdoTerminate(
>      ThreadJoin(Fdo->DevicePowerThread);
>      Fdo->DevicePowerThread = NULL;
> 
> -    // stop frontend thread
> -    ThreadAlert(Fdo->FrontendThread);
> -    ThreadJoin(Fdo->FrontendThread);
> -    Fdo->FrontendThread = NULL;
> -
>      // stop enum thread
>      ThreadAlert(Fdo->ScanThread);
>      ThreadJoin(Fdo->ScanThread);
> diff --git a/src/xenvbd/frontend.c b/src/xenvbd/frontend.c
> index 4a8fbe3..1436001 100644
> --- a/src/xenvbd/frontend.c
> +++ b/src/xenvbd/frontend.c
> @@ -41,6 +41,7 @@
>  #include "notifier.h"
>  #include "blockring.h"
>  #include "granter.h"
> +#include "thread.h"
>  #include <store_interface.h>
>  #include <suspend_interface.h>
> 
> @@ -76,7 +77,7 @@ struct _XENVBD_FRONTEND {
> 
>      // Backend State Watch
>      BOOLEAN                     Active;
> -    PKEVENT                     BackendEvent;
> +    PXENVBD_THREAD              BackendThread;
>      PXENBUS_STORE_WATCH         BackendWatch;
>  };
> 
> @@ -925,7 +926,7 @@ FrontendPrepare(
>                            Frontend->Store,
>                            NULL,
>                            Frontend->BackendPath,
> -                          Frontend->BackendEvent,
> +                          ThreadGetEvent(Frontend->BackendThread),
>                            &Frontend->BackendWatch);
>      if (!NT_SUCCESS(Status))
>          goto fail2;
> @@ -1502,21 +1503,32 @@ FrontendSetState(
>      return Status;
>  }
> 
> -__drv_requiresIRQL(DISPATCH_LEVEL)
> -VOID
> -FrontendBackendPathChanged(
> -    __in  PXENVBD_FRONTEND        Frontend
> +__checkReturn
> +static DECLSPEC_NOINLINE NTSTATUS
> +FrontendBackend(
> +    __in PXENVBD_THREAD              Thread,
> +    __in PVOID                       Context
>      )
>  {
> -    KIRQL       Irql;
> -    KeAcquireSpinLock(&Frontend->StateLock, &Irql);
> -    // Only attempt this if Active, Active is set/cleared on D3->D0/D0->D3
> -    if (Frontend->Active) {
> -        // Note: Nothing may have changed with this target, this could be
> caused by another target changing
> -        __ReadDiskInfo(Frontend);
> -        __CheckBackendForEject(Frontend);
> +    PXENVBD_FRONTEND                Frontend = Context;
> +
> +    for (;;) {
> +        KIRQL       Irql;
> +
> +        if (ThreadWait(Thread))
> +            break;
> +
> +        KeAcquireSpinLock(&Frontend->StateLock, &Irql);
> +        // Only attempt this if Active, Active is set/cleared on 
> D3->D0/D0->D3
> +        if (Frontend->Active) {
> +            __ReadDiskInfo(Frontend);
> +            __CheckBackendForEject(Frontend);
> +        }
> +        KeReleaseSpinLock(&Frontend->StateLock, Irql);
>      }
> -    KeReleaseSpinLock(&Frontend->StateLock, Irql);
> +
> +    return STATUS_SUCCESS;
> +
>  }
> 
>  __checkReturn
> @@ -1525,7 +1537,6 @@ FrontendCreate(
>      __in  PXENVBD_PDO             Pdo,
>      __in  PCHAR                   DeviceId,
>      __in  ULONG                   TargetId,
> -    __in  PKEVENT                 Event,
>      __out PXENVBD_FRONTEND*       _Frontend
>      )
>  {
> @@ -1547,7 +1558,6 @@ FrontendCreate(
>      Frontend->State = XENVBD_INITIALIZED;
>      Frontend->DiskInfo.SectorSize = 512; // default sector size
>      Frontend->BackendId = DOMID_INVALID;
> -    Frontend->BackendEvent = Event;
> 
>      Status = STATUS_INSUFFICIENT_RESOURCES;
>      Frontend->FrontendPath = DriverFormat("device/%s/%s",
> FdoEnum(PdoGetFdo(Pdo)), DeviceId);
> @@ -1570,6 +1580,10 @@ FrontendCreate(
>      if (!NT_SUCCESS(Status))
>          goto fail6;
> 
> +    Status = ThreadCreate(FrontendBackend, Frontend, &Frontend-
> >BackendThread);
> +    if (!NT_SUCCESS(Status))
> +        goto fail7;
> +
>      // kernel objects
>      KeInitializeSpinLock(&Frontend->StateLock);
> 
> @@ -1577,6 +1591,10 @@ FrontendCreate(
>      *_Frontend = Frontend;
>      return STATUS_SUCCESS;
> 
> +fail7:
> +    Error("fail7\n");
> +    GranterDestroy(Frontend->Granter);
> +    Frontend->Granter = NULL;
>  fail6:
>      Error("fail6\n");
>      BlockRingDestroy(Frontend->BlockRing);
> @@ -1614,6 +1632,10 @@ FrontendDestroy(
>      PdoFreeInquiryData(Frontend->Inquiry);
>      Frontend->Inquiry = NULL;
> 
> +    ThreadAlert(Frontend->BackendThread);
> +    ThreadJoin(Frontend->BackendThread);
> +    Frontend->BackendThread = NULL;
> +
>      GranterDestroy(Frontend->Granter);
>      Frontend->Granter = NULL;
> 
> diff --git a/src/xenvbd/frontend.h b/src/xenvbd/frontend.h
> index 7d934f9..7e40bce 100644
> --- a/src/xenvbd/frontend.h
> +++ b/src/xenvbd/frontend.h
> @@ -171,19 +171,12 @@ FrontendSetState(
>      __in  XENVBD_STATE            State
>      );
> 
> -__drv_requiresIRQL(DISPATCH_LEVEL)
> -extern VOID
> -FrontendBackendPathChanged(
> -    __in  PXENVBD_FRONTEND        Frontend
> -    );
> -
>  __checkReturn
>  extern NTSTATUS
>  FrontendCreate(
>      __in  PXENVBD_PDO             Pdo,
>      __in  PCHAR                   DeviceId,
>      __in  ULONG                   TargetId,
> -    __in  PKEVENT                 Event,
>      __out PXENVBD_FRONTEND*       _Frontend
>      );
> 
> diff --git a/src/xenvbd/pdo.c b/src/xenvbd/pdo.c
> index c7d8b2b..918b824 100644
> --- a/src/xenvbd/pdo.c
> +++ b/src/xenvbd/pdo.c
> @@ -2458,15 +2458,6 @@ PdoIssueDeviceEject(
>      }
>  }
> 
> -__drv_requiresIRQL(DISPATCH_LEVEL)
> -VOID
> -PdoBackendPathChanged(
> -    __in PXENVBD_PDO             Pdo
> -    )
> -{
> -    FrontendBackendPathChanged(Pdo->Frontend);
> -}
> -
>  __checkReturn
>  NTSTATUS
>  PdoD3ToD0(
> @@ -2538,7 +2529,6 @@ PdoCreate(
>      __in PXENVBD_FDO             Fdo,
>      __in __nullterminated PCHAR  DeviceId,
>      __in ULONG                   TargetId,
> -    __in PKEVENT                 FrontendEvent,
>      __in XENVBD_DEVICE_TYPE      DeviceType
>      )
>  {
> @@ -2569,15 +2559,14 @@ PdoCreate(
>      QueueInit(&Pdo->PreparedReqs);
>      QueueInit(&Pdo->SubmittedReqs);
>      QueueInit(&Pdo->ShutdownSrbs);
> -
> -    Status = FrontendCreate(Pdo, DeviceId, TargetId, FrontendEvent, &Pdo-
> >Frontend);
> -    if (!NT_SUCCESS(Status))
> -        goto fail2;
> -
>      __LookasideInit(&Pdo->RequestList, sizeof(XENVBD_REQUEST),
> REQUEST_POOL_TAG);
>      __LookasideInit(&Pdo->SegmentList, sizeof(XENVBD_SEGMENT),
> SEGMENT_POOL_TAG);
>      __LookasideInit(&Pdo->IndirectList, sizeof(XENVBD_INDIRECT),
> INDIRECT_POOL_TAG);
> 
> +    Status = FrontendCreate(Pdo, DeviceId, TargetId, &Pdo->Frontend);
> +    if (!NT_SUCCESS(Status))
> +        goto fail2;
> +
>      Status = PdoD3ToD0(Pdo);
>      if (!NT_SUCCESS(Status))
>          goto fail3;
> @@ -2595,14 +2584,14 @@ fail4:
> 
>  fail3:
>      Error("Fail3\n");
> -    __LookasideTerm(&Pdo->IndirectList);
> -    __LookasideTerm(&Pdo->SegmentList);
> -    __LookasideTerm(&Pdo->RequestList);
>      FrontendDestroy(Pdo->Frontend);
>      Pdo->Frontend = NULL;
> 
>  fail2:
>      Error("Fail2\n");
> +    __LookasideTerm(&Pdo->IndirectList);
> +    __LookasideTerm(&Pdo->SegmentList);
> +    __LookasideTerm(&Pdo->RequestList);
>      __PdoFree(Pdo);
> 
>  fail1:
> @@ -2665,13 +2654,13 @@ PdoDestroy(
>      ASSERT3S(Pdo->ReferenceCount, ==, 0);
>      ASSERT3U(PdoGetDevicePnpState(Pdo), ==, Deleted);
> 
> +    FrontendDestroy(Pdo->Frontend);
> +    Pdo->Frontend = NULL;
> +
>      __LookasideTerm(&Pdo->IndirectList);
>      __LookasideTerm(&Pdo->SegmentList);
>      __LookasideTerm(&Pdo->RequestList);
> 
> -    FrontendDestroy(Pdo->Frontend);
> -    Pdo->Frontend = NULL;
> -
>      ASSERT3U(Pdo->Signature, ==, PDO_SIGNATURE);
>      RtlZeroMemory(Pdo, sizeof(XENVBD_PDO));
>      __PdoFree(Pdo);
> diff --git a/src/xenvbd/pdo.h b/src/xenvbd/pdo.h
> index 3bff743..946c34f 100644
> --- a/src/xenvbd/pdo.h
> +++ b/src/xenvbd/pdo.h
> @@ -55,7 +55,6 @@ PdoCreate(
>      __in PXENVBD_FDO             Fdo,
>      __in __nullterminated PCHAR  DeviceId,
>      __in ULONG                   TargetId,
> -    __in PKEVENT                 FrontendEvent,
>      __in XENVBD_DEVICE_TYPE      DeviceType
>      );
> 
> @@ -75,12 +74,6 @@ PdoD0ToD3(
>      __in PXENVBD_PDO             Pdo
>      );
> 
> -__drv_requiresIRQL(DISPATCH_LEVEL)
> -extern VOID
> -PdoBackendPathChanged(
> -    __in PXENVBD_PDO             Pdo
> -    );
> -
>  // PnP States
>  extern VOID
>  PdoSetMissing(
> --
> 1.9.4.msysgit.1
> 
> 
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> win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> http://lists.xenproject.org/cgi-bin/mailman/listinfo/win-pv-devel
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