How to accelerate std::wofstream

I have the following code that performs writing into std::wofstream (with conversion into UTF-8):

std::wofstream stream;
stream.open(L"D:\\MyFile.txt", std::ios_base::app | std::ios_base::out);

std::locale utf8locale = <Get UTF-8 locale>;
stream.imbue(utf8locale);

int i;
for (i = 0; i < 700000; ++i)
{
stream.write(L"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA", 150);
}
stream.close();

This works too slowly — on computer P-4 3GHz the code (output file is 10 Mb) takes 4.1 sec.
Is it possible to accelerate it?

I have tried to large buffer for the stream (stream.rdbuf()->pubsetbuf(...)) — size of 200 Kb. But this gave no acceleration.

The compiler is MS Visual Studio 2005; Windows XP

Try turning off sync_with_stdio. Might have significant impact.

>for (i = 0; i < 700000; ++i)

Sorry, misprint - in fact, there is '70000' in the program, not '700000" (extra zero). So the output file is, really, about 10 Mb. The time is, as I said, 4.1 sec.

Quote:

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Originally Posted by treuss

Try turning off sync_with_stdio. Might have significant impact.

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I have tried - no effect.

BTW, when I tried to use std::ofstream instead of std::wofstream - the time was 200 ms! 20 times faster!!

Quote:

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Originally Posted by KellyLynch

I have tried - no effect.

BTW, when I tried to use std::ofstream instead of std::wofstream - the time was 200 ms! 20 times faster!!

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Are you timing a release build or a debug build?

Regards,

Paul McKenzie

Not sure but try concatenating the string first and write in one go

Quote:

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Originally Posted by Paul McKenzie

Are you timing a release build or a debug build?

Regards,

Paul McKenzie

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Release

for windows try this funtion:

http://undocumented.ntinternals.net/...WriteFile.html

Quote:

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Originally Posted by Mitsukai

for windows try this funtion:

http://undocumented.ntinternals.net/...WriteFile.html

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NtWriteFile? I do not think this is what I need. I need to somehow imrpove performance of std::wofstream; not just 'write blocks of bytes into a file'.

and how does NtWriteFile not do what u want but faster?

Quote:

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Originally Posted by Mitsukai

and how does NtWriteFile not do what u want but faster?

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NtWriteFile is writing buffer of bytes into file, right? And I need streamed output - using std::wfostream or some other stream. More exactly, I need WCHAR-based stream - because of my output file is Unicode UTF-8.