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bd907fb638
The current implementation calls both pack() and Buffer.write() Size
times. The new implementation calls both of these methods only once; the
full data to write are constructed locally [1]. The range() function is
replaced by xrange() because the latter is supposed to be faster / lighter
weight [2].
On my laptop, I tested the change as follows: I pre-built the series at
[3] with
build -a X64 -p OvmfPkg/OvmfPkgX64.dsc -t GCC48 -b DEBUG \
-D HTTP_BOOT_ENABLE -D SECURE_BOOT_ENABLE
(The series at [3] is relevant because it increases the size of one of the
padded regions by 8.5 MB, slowing down the build quite a bit.)
With all source code already compiled, repeating the above command takes
approximately 45 seconds. With the patch applied, it goes down to 29
seconds.
[1] http://stackoverflow.com/questions/27384093/fastest-way-to-write-huge-data-in-file
[2] https://docs.python.org/2/library/functions.html?highlight=xrange#xrange
[3] http://thread.gmane.org/gmane.comp.bios.edk2.devel/14214
We can also measure the impact with a synthetic test:
> import timeit
>
> test_old = """
> import struct, string, StringIO
> Size = (8 * 1024 + 512) * 1024
> Buffer = StringIO.StringIO()
> PadData = 0xFF
> for i in range(0, Size):
> Buffer.write(struct.pack('B', PadData))
> """
>
> test_new = """
> import struct, string, StringIO
> Size = (8 * 1024 + 512) * 1024
> Buffer = StringIO.StringIO()
> PadByte = struct.pack('B', 0xFF)
> PadData = string.join(PadByte for i in xrange(0, Size))
> Buffer.write(PadData)
> """
>
> print(timeit.repeat(stmt=test_old, number=1, repeat=3))
> print(timeit.repeat(stmt=test_new, number=1, repeat=3))
The output is
[8.231637001037598, 8.81188416481018, 8.948754072189331]
[0.5503702163696289, 0.5461571216583252, 0.578315019607544]
Cc: Yonghong Zhu <yonghong.zhu@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
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|---|---|---|
| .. | ||
| AutoGen | ||
| BPDG | ||
| build | ||
| Common | ||
| CommonDataClass | ||
| Ecc | ||
| Eot | ||
| GenFds | ||
| GenPatchPcdTable | ||
| PatchPcdValue | ||
| Rsa2048Sha256Sign | ||
| Table | ||
| TargetTool | ||
| Trim | ||
| UPT | ||
| Workspace | ||
| GNUmakefile | ||
| Makefile | ||
| sitecustomize.py | ||