[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] OVMF very slow on AMD
On 07/28/2016 03:44 PM, Andrew Cooper wrote: >>>> As far as Intel vs AMD implementation in Xen, we have vmx_handle_cd() >>>> but no corresponding SVM code. Could it be that we need to set gPAT, for >>>> example? >>> A better approach would be to find out why ovmf insists on disabling >>> caches at all. Even if we optimise the non-PCI-device case in the >>> hypervisor, a passthrough case will still run like treacle if caches are >>> disabled. >> True, we should understand why OVMF does this. But I think we also need >> to understand what makes Intel run faster. Or is it already clear from >> vmx_handle_cd()? > Wow this code is hard to follow :( > > handle_cd() is only called when an IOMMU is enabled and the domain in > question has access to real ioports or PCI devices. > > However, I really can't spot anything that ends up eliding the > cache-disable setting even for Intel. This clearly needs further > investigation. So as an easy start perhaps Anthony could check whether this call is made with his guest running on Intel. -boris _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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