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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: Thu, 30 May 2024 10:40:09 +0300
Organization: A noiseless patient Spider
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Message-ID: <20240530104009.00005a6f@yahoo.com>
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On Thu, 30 May 2024 00:40:07 -0400
Paul <nospam@needed.invalid> wrote:

> On 5/28/2024 6:24 PM, Michael S wrote:
> > 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.  
> 
> WSL uses containers, <snip>

It seems, you are discussing a speed of access and methods of access
from the host side. My question is opposite - is access from Linux
guest to Windows host files running at the same speed as Linux (WSL,
not WSL2) guest to its own file system?
I heard that it isn't, but it was not conclusive and with insufficient
details. I am going to test our specific case of big files. Now.