rctl limit cpu

Hello.
I see in rctl man page, that I can limit cpu time in milliseconds, e.g., 
for jail. But I can't deny allocation of the resource (according to man 
page).
In Solaris I can assign different amount of cpu shares to different 
projects. How can I achieve this with rctl? For example, I'd like to 
give jail:www 40% CPU, jail:db - 50% CPU and leave 10% to the base system...
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Best regards,
Alexander Pyhalov,
system administrator of Computer Center of Southern Federal University