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

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Oct 18, 2016 at 12:07:20PM +1100, Alexey Kardashevskiy wrote:
> Ping, anyone?
> 
> I rather expected floods of mails on such a controversial topic :)

I think it's the reverse of the bike-shed problem.  Hardly anyone
feels qualified to comment on it.

It looks ok to me, but I just don't know if there are other subtle
dependencies on the size of the cpumask buried in the code.

Oh well,  let's say:

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

and find any problems as they arise.

Not sure who we need to convince to take this into their tree though.

> 
> 
> On 11/10/16 09:19, Alexey Kardashevskiy wrote:
> > Ping, anyone?
> > 
> > 
> > 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 {
> >>
> > 
> > 
> 
> 

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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