Messages in this thread Patch in this message | | | From | Paul Menzel <> | Subject | [PATCH] smpboot: reuse timer calibration | Date | Tue, 29 Oct 2019 15:19:57 +0100 |
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From: Arjan van de Ven <arjan@linux.intel.com> Date: Wed, 11 Feb 2015 17:28:14 -0600
NO point recalibrating for known-constant tsc ... saves 200ms+ of boot time.
Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de> ---
Arjan, can your Signed-off-by line be added? On what device, did you test this?
This upstreams the patch from Clear Linux.
https://github.com/clearlinux-pkgs/linux/blob/master/0108-smpboot-reuse-timer-calibration.patch
arch/x86/kernel/tsc.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index c59454c382fd..42b07ed467d2 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -1525,6 +1525,9 @@ unsigned long calibrate_delay_is_known(void) if (!constant_tsc || !mask) return 0;
+ if (cpu != 0) + return cpu_data(0).loops_per_jiffy; + sibling = cpumask_any_but(mask, cpu); if (sibling < nr_cpu_ids) return cpu_data(sibling).loops_per_jiffy; -- 2.24.0.rc1
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