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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <b8722427-cf1e-459f-8bad-04f89fb5ffc6@lucifer.local>
Date: Fri, 26 Jul 2024 19:12:56 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Linus Torvalds <torvalds@...uxfoundation.org>
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, Jul 24, 2024 at 12:52:13PM GMT, Linus Torvalds wrote:
> 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

Agreed, have generated these numbers:

## CONFIG_XEN not set

### Not Reverted

8,413,999,318 bytes

### With Laight's patch series applied

8,237,750,156 bytes (~2.1% improvement)

### Reverted

8,157,201,494 bytes (~3.1% improvement)

## CONFIG_XEN set

### Not Reverted

9,006,361,868 bytes

51,407,944	./arch/x86/xen/setup.o.pre

### With Laight's patch series applied

8,781,003,140 bytes (~2.5% improvement)

4,819,999	./arch/x86/xen/setup.o.pre (!)

### Reverted

8,699,892,262 bytes (~3.4% improvement)

5,447,539	./arch/x86/xen/setup.o.pre