Commit 69f8aeab authored Mar 04, 2022 by Peter Zijlstra Committed by Greg Kroah-Hartman Mar 15, 2022

x86/tsc: Be consistent about use_tsc_delay()



Currently loops_per_jiffy is set in tsc_early_init(), but then don't
switch to delay_tsc, with the result that delay_loop is used with
loops_per_jiffy set for delay_tsc.

Then in (late) tsc_init() lpj_fine is set (which is mostly unused) and
after which use_tsc_delay() is finally called.

Move both loops_per_jiffy and use_tsc_delay() into
tsc_enable_sched_clock() which is called the moment tsc_khz is
determined, be it early or late. Keeping the lot consistent.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220304152135.914397165@infradead.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 977b9481

arch/x86/kernel/tsc.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -1487,6 +1487,9 @@ static unsigned long __init get_loops_per_jiffy(void)

		static void __init tsc_enable_sched_clock(void)
		{
		loops_per_jiffy = get_loops_per_jiffy();
		use_tsc_delay();

		/* Sanitize TSC ADJUST before cyc2ns gets initialized */
		tsc_store_and_check_tsc_adjust(true);
		cyc2ns_init_boot_cpu();
		@@ -1502,8 +1505,6 @@ void __init tsc_early_init(void)
		return;
		if (!determine_cpu_tsc_frequencies(true))
		return;
		loops_per_jiffy = get_loops_per_jiffy();

		tsc_enable_sched_clock();
		}

		@@ -1537,7 +1538,6 @@ void __init tsc_init(void)
		enable_sched_clock_irqtime();

		lpj_fine = get_loops_per_jiffy();
		use_tsc_delay();

		check_system_tsc_reliable();