From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH V3 0/4] genirq/affinity: irq vector spread among online CPUs as far as possible To: "Rafael J. Wysocki" CC: Thomas Gleixner , Ming Lei , Artem Bityutskiy , Jens Axboe , Christoph Hellwig , Linux Kernel Mailing List , , Laurence Oberman References: <20180308105358.1506-1-ming.lei@redhat.com> <1520515113.20980.31.camel@gmail.com> <20180308133440.GA2713@ming.t460p> <20180309012458.GD5228@ming.t460p> <20180309120833.GB30257@ming.t460p> <5e5f3852-5314-c479-245e-d0a575e533a5@cn.fujitsu.com> From: Dou Liyang Message-ID: Date: Wed, 14 Mar 2018 11:30:56 +0800 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed List-ID: Hi Rafael, Thank you so much for your reply. At 03/13/2018 05:25 PM, Rafael J. Wysocki wrote: > On Tue, Mar 13, 2018 at 4:11 AM, Dou Liyang wrote: >> Hi Thomas, >> >> At 03/09/2018 11:08 PM, Thomas Gleixner wrote: >> [...] >>> >>> >>> I'm not sure if there is a clear indicator whether physcial hotplug is >>> supported or not, but the ACPI folks (x86) and architecture maintainers >> >> +cc Rafael >> >>> should be able to answer that question. I have a machine which says: >>> >>> smpboot: Allowing 128 CPUs, 96 hotplug CPUs >>> >>> There is definitely no way to hotplug anything on that machine and sure >>> the >> >> >> AFAIK, in ACPI based dynamic reconfiguration, there is no clear >> indicator. In theory, If the ACPI tables have the hotpluggable >> CPU resources, the OS can support physical hotplug. > > In order for the ACPI-based CPU hotplug (I mean physical, not just the > software offline/online we do in the kernel) to work, there have to be > objects in the ACPI namespace corresponding to all of the processors > in question. > > If they are not present, there is no way to signal insertion and eject > the processors safely. Yes, I see. Thanks dou > > >