From 5d2a4e91a541cb04d20d11602f0f9340291322ac Mon Sep 17 00:00:00 2001 From: Pavel Tatashin Date: Thu, 19 Jul 2018 16:55:41 -0400 Subject: sched/clock: Move sched clock initialization and merge with generic clock sched_clock_postinit() initializes a generic clock on systems where no other clock is provided. This function may be called only after timekeeping_init(). Rename sched_clock_postinit to generic_clock_inti() and call it from sched_clock_init(). Move the call for sched_clock_init() until after time_init(). Suggested-by: Peter Zijlstra 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: 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/20180719205545.16512-23-pasha.tatashin@oracle.com --- init/main.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'init/main.c') diff --git a/init/main.c b/init/main.c index 3b4ada11ed52..162d931c9511 100644 --- a/init/main.c +++ b/init/main.c @@ -79,7 +79,7 @@ #include #include #include -#include +#include #include #include #include @@ -642,7 +642,7 @@ asmlinkage __visible void __init start_kernel(void) softirq_init(); timekeeping_init(); time_init(); - sched_clock_postinit(); + sched_clock_init(); printk_safe_init(); perf_event_init(); profile_init(); -- cgit v1.2.3 From 857baa87b6422bcfb84ed3631d6839920cb5b09d Mon Sep 17 00:00:00 2001 From: Pavel Tatashin Date: Thu, 19 Jul 2018 16:55:42 -0400 Subject: sched/clock: Enable sched clock early Allow sched_clock() to be used before schec_clock_init() is called. This provides a way to get early boot timestamps on machines with unstable clocks. 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/20180719205545.16512-24-pasha.tatashin@oracle.com --- init/main.c | 2 +- kernel/sched/clock.c | 20 +++++++++++++++++++- 2 files changed, 20 insertions(+), 2 deletions(-) (limited to 'init/main.c') diff --git a/init/main.c b/init/main.c index 162d931c9511..ff0a24170b95 100644 --- a/init/main.c +++ b/init/main.c @@ -642,7 +642,6 @@ asmlinkage __visible void __init start_kernel(void) softirq_init(); timekeeping_init(); time_init(); - sched_clock_init(); printk_safe_init(); perf_event_init(); profile_init(); @@ -697,6 +696,7 @@ asmlinkage __visible void __init start_kernel(void) acpi_early_init(); if (late_time_init) late_time_init(); + sched_clock_init(); calibrate_delay(); pid_idr_init(); anon_vma_init(); diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c index 0e9dbb2d9aea..422cd63f8f17 100644 --- a/kernel/sched/clock.c +++ b/kernel/sched/clock.c @@ -202,7 +202,25 @@ static void __sched_clock_gtod_offset(void) void __init sched_clock_init(void) { + unsigned long flags; + + /* + * Set __gtod_offset such that once we mark sched_clock_running, + * sched_clock_tick() continues where sched_clock() left off. + * + * Even if TSC is buggered, we're still UP at this point so it + * can't really be out of sync. + */ + local_irq_save(flags); + __sched_clock_gtod_offset(); + local_irq_restore(flags); + sched_clock_running = 1; + + /* Now that sched_clock_running is set adjust scd */ + local_irq_save(flags); + sched_clock_tick(); + local_irq_restore(flags); } /* * We run this as late_initcall() such that it runs after all built-in drivers, @@ -356,7 +374,7 @@ u64 sched_clock_cpu(int cpu) return sched_clock() + __sched_clock_offset; if (unlikely(!sched_clock_running)) - return 0ull; + return sched_clock(); preempt_disable_notrace(); scd = cpu_sdc(cpu); -- cgit v1.2.3