On Mon, Dec 16, 2019 at 02:00:58PM -0500, Michael Shell wrote:
>
> Also, there is a patch for the kernel source that enables additional
> processor types and CPU specific optimizations:
>
> https://github.com/graysky2/kernel_gcc_patch
>
> IMHO, this patch should be accepted into the mainstream kernel tree.
>
>
> Cheers,
>
> Mike Shell
>
Hi Mike,
from memory the x86 maintainers were not keen on the patch because
it could make things harder to debug. Although I would like to be
able to say "this one goes up to eleven", on a completed system the
optimizations for the kernel (assuming -Os is not used!) are the
least of the slowdowns.
And since most distros (with the likely exception of gentoo) do not
optimize for the running processor, it doesn't seem liekly to be
very important for normal use. Oh, wait, intel's Clear linux ships
binaries with lots of variations for specific intel
micro-architectures (if I've understood reviews at phoronix
correctly).
But long story short: if something in the kernel gives a problem
while using it, upstream won't be interested unless it can be
replicated without using it. Personally I've got enough problems on
my Picasso (works fine, except there is what I think is an oops
during bringing up amdgpu with all versions of the kernel new enough
to be able to do that - i.e. 5.0 and later) to not try this.
OTOH speed-ups, particularly on intel in the light of their
vulnerabilities and the slowdowns from newer microcode, are always
welcome so (like -march=native which I mostly use in userspace,
along with a choice of CFLAGS/CXXFLAGS) people should be encouraged
to experiment if they understand the potential downsides. ;-)
ĸen
--
We've all got both light and dark inside of us.
What matters is the part we choose to act on.
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