Originally posted by sdack
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Clang PGO Shot Down For Now From The Linux Kernel
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As GCC and Clang differ in some ways in collecting and using profiles, I cannot see a problem here with using distinct PGO infrastructure for both compilers (unifying this beteween GCC and Clang would be a nice bonus, but unrealistic to happen anytime soon). It is also better supported, so going the perf-route doesn't seem to be the obvious better option here in my eyes.
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Originally posted by nemequ View PostSo he wants to hold off for a little while to do it right.
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In Ukraine, when our corrupt government is slowing down reforms, we say «зрада» (”betrayal”).
Michael, Unicode input via hex keyboard from macOS is somewhat broken here. E.g. when I try to input guillemets (‘«’ and ‘»’) via ⌥+00ab and ⌥+00bb, ⌥+0 triggers forum hotkeys tutorial
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A later post explains his reasoning a bit better:
I agree that perf profiling works best on Intel. The AMD perf side works ok in Zen 2 from what I've seen, but needs to be a full-system profile ("perf record -a") to use the better options, and ARM is..
But with x86 ranging from "excellent" to "usable", and ARM hopefully being at least close to getting better proper profile data, I really think it's the way forward, with instrumentation being a band-aid at best.
Linus
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Originally posted by CochainComplex View Post
same here. I don't understand why perf is in favor of clang if it is obviously inferior (according to michaels arguments). Is it possible that Linus is not full aware of the whole scope? But I do understand that one compiler independent solution is preferable
As a result, what you measure is not the real performance of the system.
He thought the existing support of linux’s perf on x86 is mature and good enough while on arm it is OK.
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Originally posted by FireBurn View PostThe Kernel built with clang is working great here on my systems with LTO, including now on my Raven machine. I've never tried PGO - always seemed like to much of a hassle to create profiles
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The Kernel built with clang is working great here on my systems with LTO, including now on my Raven machine. I've never tried PGO - always seemed like to much of a hassle to create profiles
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Clang PGO Shot Down For Now From The Linux Kernel
Phoronix: Clang PGO Shot Down For Now From The Linux Kernel
While Clang PGO support was sent in for Linux 5.14 as part of Clang compiler handling updates for this next kernel version, the functionality was subsequently dropped out and a new pull request issued after criticism from Linus Torvalds and others...
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