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

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Message-ID: <CAHk-=wjCV+RmhWjh2Dsdki6FfqZDkM9JMQ=Qw9zGmGQD=ir6cw@mail.gmail.com>
Date: Wed, 24 Jul 2024 12:52:13 -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 Wed, 24 Jul 2024 at 12:35, Lorenzo Stoakes
<lorenzo.stoakes@...cle.com> wrote:
>
> My rough numbers below, on a 32-core intel i9-14900KF box using defconfig +
> a small number of debug flags I use for compiler development:

Side note: I think better than "time it" would be to simply generate
all the pre-processor files, and look at the size.

Because to a very close approximation, all the overhead from these
things comes from the deep macro expansions.

And unlike timings, the pre-processor size is going to be (a) entirely
repeatable, and (b) will also perhaps point out other worst-case
scenarios. IOW, maybe there is something else that looks like that
"min3()" horror, that can be more surgically fixed.

                 Linus