x86/smpboot: Avoid pointless delay calibration if TSC is synchronized

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When TSC is synchronized across sockets then there is no reason to
calibrate the delay for the first CPU which comes up on a socket.

Just reuse the existing calibration value.

This removes 100ms pointlessly wasted time from CPU hotplug per socket.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Helge Deller <deller@gmx.de> # parisc
Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com> # Steam Deck
Link: https://lore.kernel.org/r/20230512205255.608773568@linutronix.de

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Thomas Gleixner 2023-05-12 23:07:01 +02:00 • committed by Peter Zijlstra

parent ba831b7b1a

commit 134a12827b

2 changed files with 41 additions and 19 deletions

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42

arch/x86/kernel/smpboot.c

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20

arch/x86/kernel/tsc.c

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