win32utils devel - Nov 2004 - nread and nwrite optimizations

Hi all,

So far, so good.  Things seem to work just fine and, in the case of
nread, I am getting incredible performance.  I can''t tell if this is
due
to some kind of caching, however.

Anyway, there a couple of things I want to work out yet.  The first is
File#nread and Really Big Files.  I created a 500 mb text file and
sucked it into memory using Ruby''s File#read method just fine. 
However,
when I tried to use File#nread, it eventually died with a memory
allocation error.  Since I have 1GB of RAM (and wasn''t using much),
I''m
not sure why it would complain.

The second issue is getting FILE_FLAG_NO_BUFFERING to work.  Mostly I
just want to see if this will lead to a significant performance increase
with reads and writes.  But, using it has certain requirements that I
don''t totally understand.

Any ideas for these two issues are definitely welcome.

Dan

Hi,
> 
> Hi all,
> 
> So far, so good.  Things seem to work just fine and, in the case of
> nread, I am getting incredible performance.  I can''t tell if this
is due
> to some kind of caching, however.
> 
> Anyway, there a couple of things I want to work out yet.  The first is
> File#nread and Really Big Files.  I created a 500 mb text file and
> sucked it into memory using Ruby''s File#read method just fine. 
However,
> when I tried to use File#nread, it eventually died with a memory
> allocation error.  Since I have 1GB of RAM (and wasn''t using
much), I''m
> not sure why it would complain.
>
For me, the memory allocation always return sucess. Even if  625 mb file
 
> The second issue is getting FILE_FLAG_NO_BUFFERING to work.  Mostly I
> just want to see if this will lead to a significant performance increase
> with reads and writes.  But, using it has certain requirements that I
> don''t totally understand.
> 
It seems that Reading the whole data with one ReadFile using
FILE_FLAG_NO_BUFFERING is not working for large file.

Refer to http://www.winimage.com/readfile.htm
It contains source code and shows various ReadFile methods.
> Any ideas for these two issues are definitely welcome.
> 
Regards,

Park Heesob



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