From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 19 Jul 2018 12:39:03 +0200 From: Peter Zijlstra Subject: Re: [PATCH v14 24/25] sched: early boot clock Message-ID: <20180719103903.GB2494@hirez.programming.kicks-ass.net> References: <20180718022211.6259-1-pasha.tatashin@oracle.com> <20180718022211.6259-25-pasha.tatashin@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180718022211.6259-25-pasha.tatashin@oracle.com> Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: Pavel Tatashin Cc: steven.sistare@oracle.com, daniel.m.jordan@oracle.com, linux@armlinux.org.uk, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, john.stultz@linaro.org, sboyd@codeaurora.org, x86@kernel.org, linux-kernel@vger.kernel.org, mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com, douly.fnst@cn.fujitsu.com, prarit@redhat.com, feng.tang@intel.com, pmladek@suse.com, gnomes@lxorguk.ukuu.org.uk, linux-s390@vger.kernel.org, boris.ostrovsky@oracle.com, jgross@suse.com, pbonzini@redhat.com List-ID: On Tue, Jul 17, 2018 at 10:22:10PM -0400, Pavel Tatashin wrote: > diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c > index 0e9dbb2d9aea..7a8a63b940ee 100644 > --- a/kernel/sched/clock.c > +++ b/kernel/sched/clock.c > @@ -202,7 +202,15 @@ static void __sched_clock_gtod_offset(void) > > void __init sched_clock_init(void) > { > + unsigned long flags; > + > sched_clock_running = 1; > + > + /* Adjust __gtod_offset for contigious transition from early clock */ > + local_irq_save(flags); > + sched_clock_tick(); > + local_irq_restore(flags); > + __sched_clock_gtod_offset(); I think we want to keep __sched_clock_gtod_offset() inside the IRQ disabled region. And I just looked at my patch: https://lkml.kernel.org/r/20180626090003.GA2458@hirez.programming.kicks-ass.net and that had a comment about how we wanted to set the gtod offset _before_ setting sched_clock_running, yet here you do it the other way around. Hmm? > } > /* > * We run this as late_initcall() such that it runs after all built-in drivers, > @@ -356,7 +364,7 @@ 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);