From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Wang, Wei W" <wei.w.wang@intel.com>
Subject: Re: [PATCH v4 04/11] x86/intel_pstate: avoid calling
 cpufreq_add_cpu() twice
Date: Mon, 27 Jul 2015 07:35:14 +0000
Message-ID: <286AC319A985734F985F78AFA26841F79E432F@shsmsx102.ccr.corp.intel.com>
References: <1435230922-22111-1-git-send-email-wei.w.wang@intel.com>
	<55B25B570200007800095344@prv-mh.provo.novell.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path: <xen-devel-bounces@lists.xen.org>
In-Reply-To: <55B25B570200007800095344@prv-mh.provo.novell.com>
Content-Language: en-US
List-Unsubscribe: <http://lists.xen.org/cgi-bin/mailman/options/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xen.org>
List-Help: <mailto:xen-devel-request@lists.xen.org?subject=help>
List-Subscribe: <http://lists.xen.org/cgi-bin/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=subscribe>
Sender: xen-devel-bounces@lists.xen.org
Errors-To: xen-devel-bounces@lists.xen.org
To: Jan Beulich <JBeulich@suse.com>
Cc: "andrew.cooper3@citrix.com" <andrew.cooper3@citrix.com>, "xen-devel@lists.xen.org" <xen-devel@lists.xen.org>
List-Id: xen-devel@lists.xenproject.org

On 24/07/2015 21:36,  Jan Beulich wrote:
> >>> On 25.06.15 at 13:15, <wei.w.wang@intel.com> wrote:
> > cpufreq_add_cpu() is already called in the hypercall code path (the
> > bottom of set_px_pminfo() and inside cpufreq_cpu_init()).
> > So, we remove the redundant calling here.
> 
> While I can see that currently the call is kind of pointless (as it can't do
> anything useful before Dom0 communicated the data obtained from ACPI),
> it's still logically correct to call the callback on the BP prior to registering a hook
> for AP bringup. Otherwise you could (and perhaps should) as well defer the
> CPU notifier registration.
> 
> Otoh now that you're trying to introduce a driver independent of ACPI (and
> hence initialized at boot time) I wonder why you don't make use of what is
> here instead of deleting it.
> 

Ok, I will roll back to leave cpufreq_presmp_init() there.

Best,
Wei
> 
> > --- a/xen/drivers/cpufreq/cpufreq.c
> > +++ b/xen/drivers/cpufreq/cpufreq.c
> > @@ -632,8 +632,6 @@ static struct notifier_block cpu_nfb = {
> >
> >  static int __init cpufreq_presmp_init(void)  {
> > -    void *cpu = (void *)(long)smp_processor_id();
> > -    cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
> >      register_cpu_notifier(&cpu_nfb);
> >      return 0;
> >  }
>