Re: cpu hotplug

[Gleb Natapov <gleb@redhat.com>]

On Sun, Sep 19, 2010 at 12:41:37PM +0200, Conrad Wood wrote:
> On Sun, 2010-09-19 at 08:38 +0200, Gleb Natapov wrote:
> > On Sat, Sep 18, 2010 at 08:27:54PM +0200, Conrad Wood wrote:
> > > On Sat, 2010-09-18 at 10:32 -0400, Kevin O'Connor wrote:
> > > > On Fri, Sep 17, 2010 at 11:39:36PM +0200, Conrad Wood wrote:
> > > > > Hi everyone,
> > > > > 
> > > > > I'm currently looking into hotplugging CPUs. 
> > > > > This exclusively with linux-guests and linux-host.
> > > > > I have found some (conflicting) information about this on the net.
> > > > > 
> [...]
> 
> Well, I got a bit further - thanks so far for your help.
> Given
> 1. kvm-72
> 2. linux-guest-kernel 2.6.35.4
> 3. kernel cmdline "maxcpus=32 possible_cpus=32"
> 
> I can set "cpu_set 5 online" in the monitor and get indeed a new cpu
> appearing in /sys/devices..., which I can then set online in the guest
> by doing echo 1 >/sys/devices/.../online.
> 
> /proc/cpuinfo in the guest then reports the new cpu.
> 
> But... why does the command "info cpus" in the monitor report all cpus
> apart from CPU0 as (halted) ?
> 
Because they are halted? Run multiple cpu hogs in the guest and see if
cpus will still be halted as reported by monitor. Also kvm-72 is so
ancient that I am not sure it reports cpu state correctly in monitor at
all.

--
			Gleb.