Re: 16 vcpus, 200GB of memory boots!!!

Zhang, Xiantao wrote:
>> I have located a 512 cpu / 1 TB system in-house that I might get my
>> hands on at some point to run tests on, but I need to work on the qemu
>> startup times first. It took well over 20 minutes for qemu to get
>> going before anything really happened.
> Hi, Jes
>     How long does it cost from efi shell to Linux's login interface ? Currently, we allocates so large memory for guests,  kvm has to pin the corresponding pages in p2m table other than allocate them on-demand, so it may cost long time to allocate every page from kernel, and fill them into p2m table. Once we support host-swapping later, the issue should disappear. But anyway, it can't lead into any performance issue after bootup.  To support larger memory than 384G, we may allocate contiguous huge pages, such as 16M, 256M pages for guest, if so, it may save many p2m entries because one entry can stand for 16M or 256M, so larger memory gets supported finally. 
> Xiantao

Hi Xiantao,

 From EFI to Linux's login wasn't bad, I didn't notice it being much
slower than on real hardware. The big issue was from QEMU until EFI,
it took probably 20 minutes or more before I started getting any of
the debug information from the firmware image on the console :-( I think
what is happening right now is something in qemu being really slow.

It's end of day here for me, but I hope to look at it tomorrow.

Cheers,
Jes