From: Peter Zijlstra <peterz@infradead.org>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Wanpeng Li <kernellwp@gmail.com>, Mike Galbraith <efault@gmx.de>,
LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
Borislav Petkov <bp@alien8.de>
Subject: Re: tip.today - scheduler bam boom crash (cpu hotplug)
Date: Mon, 27 Feb 2017 21:35:49 +0100 [thread overview]
Message-ID: <20170227203549.GA6500@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1104576579.26276825.1488222387110.JavaMail.zimbra@redhat.com>
On Mon, Feb 27, 2017 at 02:06:27PM -0500, Paolo Bonzini wrote:
> > > + if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
> > > + mark_tsc_unstable("not invariant");
> >
> > Errm, no.
> >
> > That makes TSC unusable for systems which do not go into C/P states in
> > which the TSC stops. There is a world outside KVM ....
>
> Actually I was surprised too by Peter's patch, as it was adding
> mark_tsc_unstable pretty much everywhere that didn't have nonstop TSC.
> But hopefully it would still be okay to call clear_sched_clock_stable
> in tsc_init, in the same way.
I was preserving the sched_clock behaviour. That said, maybe we can
simply remove all those extra checks and only rely on the current
mark_tsc_unstable() calls.
I'll just have to sit down and consider the various cases..
next prev parent reply other threads:[~2017-02-27 22:55 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-19 7:31 tip.today - scheduler bam boom crash (cpu hotplug) Mike Galbraith
2017-01-19 10:19 ` Peter Zijlstra
2017-01-19 11:39 ` Mike Galbraith
2017-01-19 13:36 ` Peter Zijlstra
2017-01-19 16:54 ` Ingo Molnar
2017-01-19 17:20 ` Peter Zijlstra
2017-01-19 20:35 ` sched/clock: Fix hotplug issue kbuild test robot
2017-01-19 20:37 ` kbuild test robot
2017-01-20 6:36 ` [tip:sched/core] sched/clock: Fix hotplug crash tip-bot for Peter Zijlstra
2017-02-27 12:30 ` tip.today - scheduler bam boom crash (cpu hotplug) Wanpeng Li
2017-02-27 12:35 ` Paolo Bonzini
2017-02-27 12:43 ` Peter Zijlstra
2017-02-27 12:50 ` Paolo Bonzini
2017-02-27 13:04 ` Peter Zijlstra
2017-02-27 15:27 ` Paolo Bonzini
2017-02-27 15:59 ` Peter Zijlstra
2017-02-27 16:11 ` Paolo Bonzini
2017-02-27 16:36 ` Peter Zijlstra
2017-02-27 17:27 ` Paolo Bonzini
2017-02-27 17:40 ` Thomas Gleixner
2017-02-27 19:06 ` Paolo Bonzini
2017-02-27 20:35 ` Peter Zijlstra [this message]
2017-02-28 1:51 ` Wanpeng Li
2017-02-28 8:08 ` Peter Zijlstra
2017-02-28 8:11 ` Wanpeng Li
2017-03-01 13:39 ` Wanpeng Li
2017-03-01 14:17 ` Peter Zijlstra
2017-02-27 13:48 ` Wanpeng Li
2017-02-27 14:05 ` Peter Zijlstra
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