linux-kernel - Re: [PATCH 0/7] minmax: reduce compilation time

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Message-ID: <CAHk-=wg7ip=Uu+xg+d7-vKS1Yt_hJHg+fJKDYgp-8W0BncUncw@mail.gmail.com>
Date: Mon, 29 Jul 2024 21:10:11 -0700
From: Linus Torvalds <torvalds@...uxfoundation.org>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: David Laight <David.Laight@...lab.com>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, 
	"Matthew Wilcox (Oracle)" <willy@...radead.org>, Christoph Hellwig <hch@...radead.org>, 
	Andrew Morton <akpm@...ux-foundation.org>, 
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, 
	Dan Carpenter <dan.carpenter@...aro.org>, Arnd Bergmann <arnd@...nel.org>, 
	"Jason@...c4.com" <Jason@...c4.com>, "pedro.falcato@...il.com" <pedro.falcato@...il.com>, 
	Mateusz Guzik <mjguzik@...il.com>, "linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: [PATCH 0/7] minmax: reduce compilation time

On Sat, 27 Jul 2024 at 09:26, Linus Torvalds
<torvalds@...uxfoundation.org> wrote:
>
>   Longest line is drivers/.../ia_css_ynr.host.c:71 (27785kB)

So that 27MB shrank to 23MB and then to "only" 1.4MB with the patches
that are now in mainline.

Now with the patch I just posted at

  https://lore.kernel.org/all/CAHk-=wgRDupSBzUX_N_Qo_eaYyDfOH=VTihhikN36cGxCc+jvg@mail.gmail.com/

that nasty line expands to "just" 82kB, and the file builds quickly.

Still not exactly small, but hey, two and a half orders of magnitude isn't bad.

And yes, that one driver is disgusting and Lorenzo had a nice patch to
change some macros to inline functions which just made the whole
problem go away, but as a test-case for horrid macro expansion of
min()/max() it was lovely.

Of course, I never did any build timings. I'm not sure how much it
actually shows up on that level. A couple of bad cases won't be *that*
noticeable when most cases aren't too horrid.

              Linus