linux-kernel - Re: [PATCH next v4 0/5] minmax: Relax type checks in min() and max().

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Date: Tue, 9 Jan 2024 07:54:17 +0100
From: Jiri Slaby <jirislaby@...nel.org>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: David Laight <David.Laight@...lab.com>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 "Matthew Wilcox (Oracle)" <willy@...radead.org>,
 Christoph Hellwig <hch@...radead.org>, "Jason A. Donenfeld" <Jason@...c4.com>
Subject: Re: [PATCH next v4 0/5] minmax: Relax type checks in min() and max().

On 08. 01. 24, 22:11, Linus Torvalds wrote:
> On Mon, 8 Jan 2024 at 12:04, Linus Torvalds
> <torvalds@...ux-foundation.org> wrote:
>>
>> So we *could* plan on that, remove the checks from min/max, and use
>> something like the attached patch.
> 
> Whee.
> 
> On my machine, that patch makes an "allmodconfig" build go from
> 
>      10:41 elapsed
> 
> to
> 
>       8:46 elapsed
> 
> so that min/max type checking is almost 20% of the build time.
> 
> Yeah, I think we need to get rid of it.
> 
> Can somebody else confirm similar time differences? Or is it just me?

openSUSE config [1] -j160 build on 160 cores on /dev/shm:
real    6m5,729s
user    551m54,756s
sys     94m36,401s

Patched:
real    6m2,908s
user    535m35,860s
sys     92m0,006s

allmodconfig:
real    7m14,514s
user    818m34,541s
sys     112m59,033s

Patched:
real    6m57,144s
user    797m25,163s
sys     110m5,316s

So yes, there is definitely a change.

[1] 
https://github.com/openSUSE/kernel-source/blob/master/config/x86_64/default

regards,
-- 
js
suse labs