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| author | duntan <dun.tan@intel.com> | 2023-05-18 15:31:01 +0800 |
|---|---|---|
| committer | mergify[bot] <37929162+mergify[bot]@users.noreply.github.com> | 2023-06-21 08:00:04 +0000 |
| commit | fcd71642df9a3a5932a2db116acc6fe23458d8f5 (patch) | |
| tree | 800f29e0162ff5128703c71c162b943da1c6a442 /MdePkg | |
| parent | 56f65e4bad770b0d33eb54b3c180c9ec5057d8f2 (diff) | |
| download | edk2-fcd71642df9a3a5932a2db116acc6fe23458d8f5.tar.gz edk2-fcd71642df9a3a5932a2db116acc6fe23458d8f5.tar.bz2 edk2-fcd71642df9a3a5932a2db116acc6fe23458d8f5.zip | |
MdePkg: Code optimization to SMM InternalAllocateAlignedPages
This commit is code optimization to InternalAllocateAlignedPages of
SmmMemoryAllocationLib which can reduce free memory fragments. Also
it can reduce one pre-allocation page.
Let's take a simple example:
The expected pages size is 8KB, Alignment value is 8KB.
In original InternalAllocateAlignedPages(), the first step is to
allocate 4 pages and then find the first 8KB-aligned address in
allocated 4 pages. If the upper limit address of allocated 4 pages
is already 8KB aligned, then the allocated 4 pages contains two
8KB-aligned 8KB ranges. The lower 2 pages will be selected and
removed from free pages. Then the higher 2 pages will be free.
Since the whole memory allocation is from high address to low
address, then the higher 2 pages cann't be merged with other free
pages, causing the free memory fragments.
However, when only allocate 3(2+2-1) pages, we can avoid the free
memory fragments in specific case. Also 3 pages must contain a
8KB-aligned 8KB range, which meets the requirement. If the upper
limit address of allocated 3 pages is 8KB-aligned, then the higher
2 pages range of allocated 3 pages is 8KB-aligned and will be
selected and removed from free pages. The remaining lower one page
of allocated 3 pages will be free and merged with left lower free
memory. This can reduce free memory fragments in smm.
Signed-off-by: Dun Tan <dun.tan@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Zhiguang Liu <zhiguang.liu@intel.com>
Diffstat (limited to 'MdePkg')
| -rw-r--r-- | MdePkg/Library/SmmMemoryAllocationLib/MemoryAllocationLib.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/MdePkg/Library/SmmMemoryAllocationLib/MemoryAllocationLib.c b/MdePkg/Library/SmmMemoryAllocationLib/MemoryAllocationLib.c index 3ab2c1ebfd..99a8259325 100644 --- a/MdePkg/Library/SmmMemoryAllocationLib/MemoryAllocationLib.c +++ b/MdePkg/Library/SmmMemoryAllocationLib/MemoryAllocationLib.c @@ -322,7 +322,7 @@ InternalAllocateAlignedPages ( // Calculate the total number of pages since alignment is larger than page size.
//
AlignmentMask = Alignment - 1;
- RealPages = Pages + EFI_SIZE_TO_PAGES (Alignment);
+ RealPages = Pages + EFI_SIZE_TO_PAGES (Alignment) - 1;
//
// Make sure that Pages plus EFI_SIZE_TO_PAGES (Alignment) does not overflow.
//
|