From 4763f03d3d186ce8a1125844790152d76804ad60 Mon Sep 17 00:00:00 2001 From: Pavel Tatashin Date: Thu, 19 Jul 2018 16:55:40 -0400 Subject: [PATCH] x86/tsc: Use TSC as sched clock early All prerequesites for enabling TSC as sched clock early in the boot process are available now: - Early attempt of TSC calibration - Early availablity of static branch patching If TSC frequency can be established in the early calibration, enable the static key which switches sched clock to use TSC. [ tglx: Massaged changelog ] Signed-off-by: Pavel Tatashin Signed-off-by: Thomas Gleixner Cc: steven.sistare@oracle.com Cc: daniel.m.jordan@oracle.com Cc: linux@armlinux.org.uk Cc: schwidefsky@de.ibm.com Cc: heiko.carstens@de.ibm.com Cc: john.stultz@linaro.org Cc: sboyd@codeaurora.org Cc: hpa@zytor.com Cc: douly.fnst@cn.fujitsu.com Cc: peterz@infradead.org Cc: prarit@redhat.com Cc: feng.tang@intel.com Cc: pmladek@suse.com Cc: gnomes@lxorguk.ukuu.org.uk Cc: linux-s390@vger.kernel.org Cc: boris.ostrovsky@oracle.com Cc: jgross@suse.com Cc: pbonzini@redhat.com Link: https://lkml.kernel.org/r/20180719205545.16512-22-pasha.tatashin@oracle.com --- arch/x86/kernel/tsc.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index 7ea0718..9277ae9 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -1408,6 +1408,7 @@ void __init tsc_early_init(void) /* Sanitize TSC ADJUST before cyc2ns gets initialized */ tsc_store_and_check_tsc_adjust(true); cyc2ns_init_boot_cpu(); + static_branch_enable(&__use_tsc); } void __init tsc_init(void) -- 2.7.4