Re: xxd -i vs DIY Was: C23 thoughts and opinions

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.