Fast Kernel Headers v2 Posted - Speeds Up Clang-Built Linux Kernel Build By ~88%

[tildearrow]

Unfortunately I don't have any Model T or any other car pictures I've taken that would be relevant... when thinking of what to add for an image around speed, Ferrari came to mind as had some pictures during an AMD party at Ferrari HQ a few years ago.

Problem is, Phoronix is a very technical site, and for technical articles it is difficult to associate images with them, especially when the concepts are so abstract that they don't exist or cannot be represented with an object.

[perpetually high]

Does anyone have this patch available in a single file by chance?

[bug77]

Holy crap. Now C isn't the fastest language to compile. Imagine if Linux was written in Pascal. Would save millions in server hardware.

Off topic, but I'm constantly amazed to keep even experienced developers that fail to grasp two simple things (imho):
1. the more featured a language is, the more it takes to compile; you want generics, type inference, even inheritance, named parameters, be prepared to pay a price
2. longer compile times are always justified when they result in faster production code (which is almost all the time); languages like Java or C# may appear fast to compile, but they do not link anything - you'll pay a hefty runtime penalty for that

More on topic, the biggest expectation I have from these patches, whenever they manage to land, is that shorter build times will make fuzzing more feasible, so a lot more bugs will be exposed and patched.

[Mark Rose]

I wonder if these header changes are going to break every external kernel module build there is?
Probably a whole lot of other stuff that are halfway between userspace and whatnot.

Does anyone know how these changes interact with existing code?
Ie, how much breakage can one expect?

It should mostly be a matter of including new header files. The function signatures and types aren't changing, just the location of their definitions. It's nothing that those who don't mainline their modules don't already deal with.

[rmfx]

Wow, feels like the v4 of the patch will enable an over 2x compile time speedup. When other devs start contributing, there will be a before and an after.

[Mark Rose]

Does anyone have this patch available in a single file by chance?

No. It's something like 100k lines. You can check out the git repository linked in the post and render the 2000+ commits to a single diff though, I imagine.

[uxmkt]

Does anyone have this patch available in a single file by chance?

Uh, just generate it yourself the way you need it?

git clone git://git.kernel.org/pub/scm/linux/kernel/git/mingo/tip.git;
cd tip; git diff c9e6606c7fe9..391ce485ced0

[tiennou]

Are you planning already some benchmark comparison between the original kernel and the fast header version ? Would be nice to confirm it doesn't generate any slowdown a runtime.

[zboszor]

Wow, feels like the v4 of the patch will enable an over 2x compile time speedup.

Do some math. It's about cutting build time by 88% now with CLANG according to Michael .
100% / (100% - 88%) = 100 / 12 = 8.3333 , i.e. over 8x speedup already.

Unless Michael misinterpreted the numbers and it's only really speeding up by 88%, which is a totally different metric which means cutting build time by about 47%:
1 / 1.88 = 0.5319

[bachchain]

Do some math. It's about cutting build time by 88% now with CLANG according to Michael .
100% / (100% - 88%) = 100 / 12 = 8.3333 , i.e. over 8x speedup already.

Unless Michael misinterpreted the numbers and it's only really speeding up by 88%, which is a totally different metric which means cutting build time by about 47%:
1 / 1.88 = 0.5319

#
# Performance counter stats for 'make -j96 vmlinux' (3 runs):
#
# (Elapsed time in seconds):
#
v5.16-rc7:
231.34 +- 0.60 secs, 15.5 builds/hour # [ vanilla baseline ]
-fast-headers-v1:
129.97 +- 0.51 secs, 27.7 builds/hour # +78.0% improvement

So, the latter