First performance numbers

[Joerg Roedel <joerg.roedel@amd.com>]

Ok, here are some performance numbers for nested svm. I ran kernbench -M
on a virtual machine with 4G RAM and 1 VCPU (since nesting SMP guests
do currently not work). I measured simple virtualization with a shadow
paging guest on bare metal and within a nested guest (same guest image)
on a nested paging enabled first level guest.

                 | Shadow Guest (100%) | Nested Guest (X)  | X
-----------------+---------------------+-------------------+--------
Elapsed Time     | 553.244 (1.21208)   | 1185.95 (20.0365) | 214.363%
User Time        | 407.728 (0.987279)  | 520.434 (8.55643) | 127.642% 
System Time      | 144.828 (0.480645)  | 664.528 (11.6648) | 458.839%
Percent CPU      | 99 (0)              | 99 (0)            | 100.000%
Context Switches | 98265.2 (183.001)   | 220015 (3302.74)  | 223.899%
Sleeps           | 49397.8 (31.0274)   | 49460.2 (364.84)  | 100.126%

So we have an overall slowdown in the first nesting level of more than
50%. Mostly because we spend so much time in the system level. Seems
there is some work to do for performance improvements :-)

Joerg

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