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

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Date: Wed, 10 Jan 2024 17:17:39 +1100
From: Stephen Rothwell <sfr@...b.auug.org.au>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Jiri Slaby <jirislaby@...il.com>, 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().

Hi Linus,

On Mon, 8 Jan 2024 13:11:12 -0800 Linus Torvalds <torvalds@...ux-foundationorg> wrote:
>
> Whee.

Yeah.

> 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?

I was hopeful, but:

no patch:

$ /usr/bin/time make ARCH=x86_64 CROSS_COMPILE=x86_64-linux-gnu- -j140 -O -s
102460.07user 3710.56system 13:29.05elapsed 13122%CPU (0avgtext+0avgdata 4023168maxresident)k
304inputs+7917056outputs (1998673major+120730959minor)pagefaults 0swaps

with patch:

$ /usr/bin/time make ARCH=x86_64 CROSS_COMPILE=x86_64-linux-gnu- -j140 -O -s
99775.75user 3684.45system 13:12.89elapsed 13048%CPU (0avgtext+0avgdata 2217536maxresident)k
64inputs+7890304outputs (2104371major+119837267minor)pagefaults 0swaps

$ x86_64-linux-gnu-gcc --version
x86_64-linux-gnu-gcc (Debian 13.2.0-7) 13.2.0
$ lscpu
Architecture:           ppc64le
  Byte Order:           Little Endian
CPU(s):                 160
  On-line CPU(s) list:  0-159
Model name:             POWER9, altivec supported
  Model:                2.2 (pvr 004e 1202)
  Thread(s) per core:   4
  Core(s) per socket:   20
  Socket(s):            2

-- 
Cheers,
Stephen Rothwell

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