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jpoling
Enthusiast
Enthusiast

Performance Tuning White Paper

I read through the "Performance Tuning Best Practices for ESX Server 3" white paper this weekend. On page 6, in the section on Memory performance best practices, there was a statement which I am struggling to understand:

"If possible, use less than 896MB of guest physical memory on Linux virtual machines. Linux uses different techniques to map memory in the kernel if the amount of physical memory is greater than 896MB. These techniques impose additional overhead on the virtual machine monitor and can result in slightly lowered performance."

How does this translate if your Linux VM is running an application such as an Oracle Database? Can this methodology be applied to any Linux VM?

Jeff

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kjb007
Immortal
Immortal

I think that "slightly lowered performance" comment is a bit dubious. I run linux vm's with 1-8 GB of RAM, and can't complain about their performance levels. If you need the RAM, and you have to run the vm, then you don't have an option, but I can't speak to a number that would show me lower performance. And, if you're using less RAM, and need more, that in and of itself reduces performance, so I'd take that comment a bit lightly.

-KjB

vExpert/VCP/VCAP vmwise.com / @vmwise -KjB
mcowger
Immortal
Immortal

It could be applied, but the effect is so small that is is completely outweighed by improved perofrmance by not being starved for memory.

--Matt

--Matt VCDX #52 blog.cowger.us