Re: [PATCH -v4 5/5] x86,smp: limit spinlock delay on virtual machines

From: Borislav Petkov
Date: Mon Feb 04 2013 - 09:02:17 EST


On Mon, Feb 04, 2013 at 08:50:33AM -0500, Rik van Riel wrote:
> We need to know whether we are actually running on top of a
> hypervisor, not whether we have the code compiled in to do so.

Oh ok, I see.

The thing is, if CONFIG_PARAVIRT_GUEST is disabled, x86_hyper won't
exist, see: http://marc.info/?l=linux-kernel&m=135936817627848&w=2

So maybe the hypervisor guest should itself take care of this and upon
init it should set the max_spinlock_delay in init_hypervisor() instead?
Seems only fair to me...

> After all, the majority of distribution kernels will have
> CONFIG_PARAVIRT_GUEST set, but the majority of those kernels
> will be running bare metal...

Yeah :-)

Thanks.

--
Regards/Gruss,
Boris.

Sent from a fat crate under my desk. Formatting is fine.
--
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/