>>> On 17.01.13 at 13:22, Matt Wilson <m...@amazon.com> wrote: > On Wed, Jan 16, 2013 at 04:22:49PM -0500, Konrad Rzeszutek Wilk wrote: >> We have the framework to use v2, but there are no backends that >> actually use it. The end result is that on PV we use v2 grants >> and on PVHVM v1. The v1 has a capacity of 512 grants per page while >> the v2 has 256 grants per page. This means we lose about 50% >> capacity - and if we want more than 16 VIFs (each VIF takes >> 512 grants), then we are hitting the max per guest of 32. >> >> Note: The hypervisor provides an over-ride for the default >> of 32 frames (pages) per guest: gnttab_max_nr_frames=X > > I think it would be better if the dom0/service domain and hypervisor > prevent the guest from setting the version to 2 if the backend isn't > going to make use of them. In the short term, we could add a Xen > option to limit the supported version to 1.
But that's something each guest has to decide for itself. Anyway - if no-one's using v2, what did it get introduced for (not only in the hypervisor, but also in the kernel)? I thought the networking drivers were intended to make use of it... Jan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
