From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeremy Fitzhardinge <jeremy@goop.org>
Subject: Re: pv 2.6.31 (kernel.org) and save/migrate fails,	domU
	BUG
Date: Wed, 25 Nov 2009 11:28:20 -0800
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To: Ian Campbell <Ian.Campbell@citrix.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>, Dan Magenheimer <dan.magenheimer@oracle.com>, "Xen-Devel (E-mail)" <xen-devel@lists.xensource.com>, Thomas Gleixner <tglx@linutronix.de>
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On 11/25/09 06:12, Ian Campbell wrote:
> tick_resume() is never called on secondary processors. Presumably this
> is because they are offlined for suspend on native and so this is
> normally taken care of in the CPU onlining path. Under Xen we keep all
> CPUs online over a suspend.
>
> This patch papers over the issue for me but I will investigate a more
> generic, less hacky, way of doing to the same.
>
> tick_suspend is also only called on the boot CPU which I presume should
> be fixed too.
>   

Yep.  I wonder how it ever worked?  There's been a fair amount of change
in the PM code, so that could have changed things.  I don't know if
there's a deep reason for not calling tick_resume() on all processors.

Rafael, tglx: suspend/resume under Xen doesn't need to hot unplug all
the CPUs, so we don't; the hypervisor can manage the context
save/restore for all CPUs.  Is there a deep reason why
timekeeping_resume() can't call the CLOCK_EVT_NOTIFY_RESUME notifier on
all online CPUs?

>  void xen_arch_resume(void)
>  {
> -	/* nothing */
> +	smp_call_function_many(cpu_online_mask, xen_vcpu_notify_restore,
> +			       (void *)CLOCK_EVT_NOTIFY_RESUME, 1);
>  }
>   

This is equivalent to smp_call_function().

    J