Installation guide

Fig u re 14 .7. T h e virt u al mach in e creat io n wiz ard
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10. Memo ry an d CPU allo cat io n
The Memory and CPU Allocation window displays. Choose appropriate values for the
virtualized CPUs and RAM allocation. These values affect the host's and guest's
performance.
Virtualized guests require sufficient physical memory (RAM) to run efficiently and effectively.
Choose a memory value which suits your guest operating system and application
requirements. Remember, Xen guests use physical RAM. Running too many guests or leaving
insufficient memory for the host system results in significant usage of virtual memory and
swapping. Virtual memory is significantly slower which causes degraded system performance
and responsiveness. Ensure that you allocate sufficient memory for all guests and the host to
operate effectively.
Assign sufficient virtual CPUs for the virtualized guest. If the guest runs a multithreaded
application, assign the number of virtualized CPUs the guest will require to run efficiently. Do
not assign more virtual CPUs than there are physical processors (or hyper-threads) available
on the host system. It is possible to over-allocate virtual processors, however, over-allocating
vCPUs has a significant, negative effect on Xen guest and host performance.
⁠Chapt er 1 4 . Inst alling Red Hat Ent erprise Linux 6 as a Xen guest o n Red Hat Ent erprise Linux 5
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