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From: Michael S <already5chosen@yahoo.com>
Newsgroups: comp.lang.c
Subject: Re: xxd -i vs DIY Was: C23 thoughts and opinions
Date: Wed, 29 May 2024 01:24:56 +0300
Organization: A noiseless patient Spider
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Message-ID: <20240529012456.000003ce@yahoo.com>
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On Tue, 28 May 2024 23:08:22 +0100
bart <bc@freeuk.com> wrote:

> On 28/05/2024 21:23, Michael S wrote:
> > On Tue, 28 May 2024 19:57:38 +0100
> > bart <bc@freeuk.com> wrote:
> >   
> 
> >> OK, I had go with your program. I used a random data file of
> >> exactly 100M bytes.
> >>
> >> Runtimes varied from 4.1 to 5 seconds depending on compiler. The
> >> fastest time was with gcc -O3.  
> 
> > 
> > It sounds like your mass storage device is much slower than aging
> > SSD on my test machine and ALOT slower than SSD of David Brown.  
> 
> 
> My machine uses an SSD.

SSDs are not created equal. Especially for writes.

> 
> However the tests were run on Windows, so I ran your program again
> under WSL; now it took 14 seconds (using both gcc-O3 and gcc-O2).
> 
> 

3 times slower ?!
I never tested it myself, but I heard that there is a significant
difference in file access speed between WSL's own file system  and
mounted Windows directories. The difference under WSL is not as big
as under WSL2 where they say that access of mounted Windows filesystem
is very slow, but still significant.
I don't know if it applies to all file sizes or only to accessing many
small files.