Re: [PATCH v2 1/3] proc_pid_fdinfo.5: Reduce indent for most of the page

[Alejandro Colomar <alx@kernel.org>]

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Hi Colin,

On Sat, Nov 02, 2024 at 11:47:14PM +0000, Colin Watson wrote:
> On Sat, Nov 02, 2024 at 10:36:20PM +0100, Alejandro Colomar wrote:
> > This is quite naive, and will not work with pages that define their own
> > stuff, since this script is not groff(1).  But it should be as fast as
> > is possible, which is what Colin wants, is as simple as it can be (and
> > thus relatively safe), and should work with most pages (as far as
> > indexing is concerned, probably all?).
> 
> I seem to be being invoked here for something I actually don't think I
> want at all, which suggests that wires have been crossed somewhere.  Can
> you explain why I'd want to replace some part of a fairly well-optimized
> and established C program with a shell pipeline?  I'm pretty certain it
> would not be faster, at least.

Are you sure?  With a small tweak, I get the following comparison:

	alx@devuan:~/src/linux/man-pages/man-pages/main$ time lexgrog man/*/* | wc
	lexgrog: can't resolve man7/groff_man.7
	  12475   99295  919842

	real	0m6.166s
	user	0m5.132s
	sys	0m1.336s
	alx@devuan:~/src/linux/man-pages/man-pages/main$ time mansect NAME man/ \
		| groff -man -Tutf8 | wc
	   9830   27109  689478

	real	0m0.156s
	user	0m0.219s
	sys	0m0.019s

Yes, I'm working with uncompressed pages.  We'd need to add support for
handling compressed pages.  Also, we'd need to compare the performance
of lexgrog(1) with compressed pages.  But for a starter, this suggests
some good performance.

(I say with a small tweak, because the version I've posted uses
 xargs -L1, but I've tested for performance without the -L1, which is
 the main bottleneck.  It has no consequences for the NAME.  I need to
 work out some nasty details with sed -n1 for the generic version,
 though.)


Have a lovely night!
Alex

-- 
<https://www.alejandro-colomar.es/>

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