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MdePkg/BaseSynchronizationLib: Do not check timeout if lock released

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Current AcquireSpinLock() will check if timeout happens when PcdSpinLockTimeout
is not zero, even though the spin lock is already released. It may do
unnecessary operation to read timer's counter. This update is trying to acquire
spin lock firstly. If it could be acquired successfully, needn't to check
timeout at all.

Cc: Michael Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jeff Fan <jeff.fan@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
This commit is contained in:
Jeff Fan
2016-03-21 13:26:46 +08:00
parent cfaaf99bdd
commit 0f18e1eda2
3 changed files with 18 additions and 18 deletions
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12
MdePkg/Library/BaseSynchronizationLib/Synchronization.c
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@ -1,7 +1,7 @@
/** @file
Implementation of synchronization functions.
Copyright (c) 2006 - 2012, Intel Corporation. All rights reserved.<BR>
Copyright (c) 2006 - 2016, Intel Corporation. All rights reserved.<BR>
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
@ -104,7 +104,11 @@ AcquireSpinLock (
INT64 Cycle;
INT64 Delta;
if (PcdGet32 (PcdSpinLockTimeout) > 0) {
if (PcdGet32 (PcdSpinLockTimeout) == 0) {
while (!AcquireSpinLockOrFail (SpinLock)) {
CpuPause ();
}
} else if (!AcquireSpinLockOrFail (SpinLock)) {
//
// Get the current timer value
//
@ -148,10 +152,6 @@ AcquireSpinLock (
Total += Delta;
ASSERT (Total < Timeout);
}
} else {
while (!AcquireSpinLockOrFail (SpinLock)) {
CpuPause ();
}
}
return SpinLock;
}