Re: [TSVN] File writing performance

Will Dean wrote:
> Both these write an identical 4000000 byte file.
> On my machine here, you get results which look like this:
>
> C Stream time: 41ms
> W32 time: 3810ms

The stdio library (at least in the good-old days) uses a 512 byte
internal buffer and only does a system call when that buffer is full. In
your example that would reduce syscalls by a factor of 128, which is
consistent with the x92 improvement. I suspect that even with a good
windows cache, the internals of a WriteFile call are so tortuous that it
is almost as bad as the old DOS calls which write a single byte directly
onto the disk. Now, as then, anything which avoids diving into the OS
will most likely save a bundle of time.

Simon

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