Re: [Qemu-devel] [PATCH RFC 0/2] numa: allocate CPUs masks dynamically

[Greg Kurz <gkurz@linux.vnet.ibm.com>]

On Thu, 17 Nov 2016 17:27:20 +1100
Alexey Kardashevskiy <aik@ozlabs.ru> wrote:

> On 17/11/16 03:02, Igor Mammedov wrote:
> > This series removes global MAX_CPUMASK_BITS constant
> > so that it won't inderectly influence maximum CPUs count
> > supported by different targets.
> > 
> > It replaces statically allocated bitmasks with dynamically
> > allocated ones using '-smp maxcpus' value for setting
> > bitmasks size.
> > That would allocate just enough memory to handle all
> > CPUs indexes that a QEMU instance would ever have.
> > 
> > CC: Alexey Kardashevskiy <aik@ozlabs.ru>
> > CC: Greg Kurz <gkurz@linux.vnet.ibm.com>
> > CC: David Gibson <david@gibson.dropbear.id.au>
> > CC: Eduardo Habkost <ehabkost@redhat.com>
> > CC: Paolo Bonzini <pbonzini@redhat.com>
> > 
> > 
> > Igor Mammedov (2):
> >   add bitmap_free() wrapper
> >   numa: make -numa parser dynamically allocate CPUs masks  
> 
> Nice, with "ulimit -n 3072", guest kernel with CONFIG_NR_CPUS=2048,
> "mc->max_cpus = 2048;" in  hw/ppc/spapr.c, and "-smp 2048,threads=8" in
> QEMU cmdline, I get all 2048 CPUs in the guest.
> 

Nice ! And mc->max_cpus in hw/ppc/spapr.c no longer depends on
MAX_CPUMASK_BITS since commit 079019f2e319b, so it is already
possible to bump that value (1024 ? 2048 ?).

Will you send a patch ?

> 
> Tested-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> 
> 
> > 
> >  include/qemu/bitmap.h   |  5 +++++
> >  include/sysemu/numa.h   |  2 +-
> >  include/sysemu/sysemu.h |  7 -------
> >  numa.c                  | 19 ++++++++++++-------
> >  vl.c                    |  5 -----
> >  5 files changed, 18 insertions(+), 20 deletions(-)
> >   
> 
>