Messages in this thread | | | Date | Wed, 18 Aug 2021 19:59:00 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH 2/2] x86, Makefile: Add new generic x86-64 settings v2/v3/v4 |
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On Wed, Aug 18, 2021 at 05:08:40PM +0200, torvic9@mailbox.org wrote: > I ran some quick checks and benchmarks, and your doubts seem to be > justified. A 5.14-rc6 kernel compiled with the default 'generic' and > one built with 'x86-64-v3' even have the exact same uncompressed file > size. Benchmarks were inconclusive as well.
Lemme preface this with a IMHO:
Yeah, those -march machine-specific compiler switches don't really show any perf improvements for kernels because, well, if you look at the instruction stream a kernel executes, there's not really a whole lot left to optimize after -O2.
Also, the percentage of time a machine spends in the kernel should be a lot smaller (orders of magnitude) than in userspace - the operative word being *should* here :-) - so there really isn't anything to optimize.
Not to say that there aren't a gazillion other places in the kernel that could use more eyes and testing. ^Hint hint^
Thx.
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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