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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 13:08:18 +0300
Organization: A noiseless patient Spider
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On Wed, 29 May 2024 10:32:29 +0200
David Brown <david.brown@hesbynett.no> wrote:

> On 29/05/2024 01:54, bart wrote:
> > On 28/05/2024 21:23, Michael S wrote:  
> >> On Tue, 28 May 2024 19:57:38 +0100  
> >   
> >>> 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.  
> > 
> > David Brown's machines are always faster than anyone else's.  
> 
> That seems /highly/ unlikely.  Admittedly the machine I tested on is 
> fairly new - less than a year old.  But it's a little NUC-style
> machine at around the $1000 price range, with a laptop processor.
> The only thing exciting about it is 64 GB ram (I like to run a lot of
> things at the same time in different workspaces).
> 

Modern laptop processors with adequate cooling can be as fast as
desktop (and faster than server) for a task that uses only 1 or 2
cores. Especially when no heavy vector math involved. If the task runs
only for few seconds, like in our tests, then they CPU can be fast even
without good cooling.
And $1000 is not exactly low price for mini-PC without display. Last
time I bought one for my mother, it costed ~$650 including Win11 Home
Ed. 

> But I am better than some people at getting my machines to run
> programs efficiently.  I don't use Windows for such things (I happily
> run Windows on a different machine for other purposes), and I
> certainly don't use layers of OS or filesystem emulation such as WSL
> and expect code to run at maximal speed.
>

WSL would not affect user-level CPU-bound part and even majority of
kernel-level CPU-bound parts. It can slow down I/O, yes. But it turned
out (see my post above) that the bottleneck was in CPU.

> And as I said in an earlier post, I didn't have the files on any kind
> of disk or SSD at all - they were all in a tmpfs filesystem to
> eliminate that bottleneck.
> 

You should have said it yesterday.