Re: [Qemu-devel] [PATCH qemu] sysemu: support up to 1024 vCPUs

[Igor Mammedov <imammedo@redhat.com>]

On Tue, 11 Oct 2016 09:19:10 +1100
Alexey Kardashevskiy <aik@ozlabs.ru> wrote:

> Ping, anyone?
I have a similar patch
http://patchwork.ozlabs.org/patch/681709/
which bumps limit to 288 and does a little bit more
so it wouldn't affect current users.

After that's merged, I plan to get rid of this limit and
make that part of numa parsing code dynamic so that it
wouldn't impose such limit/any limits on target code.

> 
> 
> On 04/10/16 11:33, Alexey Kardashevskiy wrote:
> > From: Greg Kurz <gkurz@linux.vnet.ibm.com>
> > 
> > Some systems can already provide more than 255 hardware threads.
> > 
> > Bumping the QEMU limit to 1024 seems reasonable:
> > - it has no visible overhead in top;
> > - the limit itself has no effect on hot paths.
> > 
> > Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
> > Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> > ---
> >  include/sysemu/sysemu.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
> > index ef2c50b..2ec0bd8 100644
> > --- a/include/sysemu/sysemu.h
> > +++ b/include/sysemu/sysemu.h
> > @@ -173,7 +173,7 @@ extern int mem_prealloc;
> >   *
> >   * Note that cpu->get_arch_id() may be larger than MAX_CPUMASK_BITS.
> >   */
> > -#define MAX_CPUMASK_BITS 255
> > +#define MAX_CPUMASK_BITS 1024
> >  
> >  #define MAX_OPTION_ROMS 16
> >  typedef struct QEMUOptionRom {
> >   
> 
>