[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH] vl.c: Check max_cpus limit instead of smp_cpus
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PATCH] vl.c: Check max_cpus limit instead of smp_cpus |
Date: |
Thu, 8 May 2014 09:26:36 +0100 |
On 7 May 2014 23:20, Andreas Färber <address@hidden> wrote:
> Am 07.05.2014 23:48, schrieb Peter Maydell:
>> This is confusing. What is max_cpus
>
> Specified via -smp, defaults to actual CPUs.
I thought that was smp_cpus ...
>> and why do we not
>> just set max_cpus = machine->max_cpus ?
>
> For the PC, machine->max_cpus specifies the technical (APIC/ACPI/...)
> upper limit, whereas -smp limits it to saner values.
>
> If you think KVM, then many machines today will have less than the
> maximum number of CPUs and you may want to run multiple VMs and you may
> not want their vCPUs competing too much for existing CPUs, so a limit
> makes sense.
That would imply that we want
max_cpus = MIN(command_line_max_cpus, machine->max_cpus);
thanks
-- PMM