Re: [PATCH 3/4] Split "auto" compression mode into its own path

[David Gibson <david@gibson.dropbear.id.au>]

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On Fri, Apr 05, 2024 at 08:10:02PM +0200, Stefano Brivio wrote:
> On Fri, 22 Mar 2024 13:27:38 +1100
> David Gibson <david@gibson.dropbear.id.au> wrote:
> 
> > mbuto supports "auto" compression mode where we detect the fastest
> > compressor and use it.  This is structured a bit oddly - cpio_compress()
> > first handles the case of an explicitly selected compressor, then handles
> > the auto-detected case, redundantly actually implementing the compression
> > once it has picked one.
> 
> Yes, we don't want to risk keeping around several formats if the
> archives are big... but you're not changing this, right?

I don't believe so, no.

> > Make this a bit clearer: first handle the "auto" case by calling out to
> > the testing code, and using that to set the parameter for the specific
> > compression path.
> > 
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > ---
> >  mbuto | 53 ++++++++++++++++++++++++-----------------------------
> >  1 file changed, 24 insertions(+), 29 deletions(-)
> > 
> > diff --git a/mbuto b/mbuto
> > index 49d032c..550f76e 100755
> > --- a/mbuto
> > +++ b/mbuto
> > @@ -566,31 +566,11 @@ cpio_init() {
> >  	fi
> >  }
> >  
> > -# cpio_compress() - Compress archive, test available methods if none is selected
> > +# compress_select() - Try compressors and pick the fastest
> 
> Now we can say we pick the fastest, but it's not clear in what: we care
> about decompression, so perhaps:
> 
> # compress_select() - Try compressors and pick the fastest to decompress image
> 
> ?

I don't think that's accurate.  AFAICT the code is selecting the
fastest to compress, not decompress, and I didn't change that.  I
agree that optimizing decompression speed would make more sense.

Honestly, I'm not really convinced that the auto mode is useful
anyway: even if we changed to decompression speed, the speed on the
location running mbuto isn't necessarily the same as on the target
doing the decompression (though given mbuto's usage model, it's
lkely).


-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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