From: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx> No point recalibrating for known-constant tsc. When tested on a 128 core, 2 socket server, this reduces the parallel smpboot time from 100ms to 30ms. Not-signed-off-by: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx> Signed-off-by: Usama Arif <usama.arif@xxxxxxxxxxxxx> --- 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 a78e73da4a74..bab8a98080cf 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -1569,6 +1569,9 @@ 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; -- 2.25.1
