Re: [RFC] CPU hard limits

From: Avi Kivity
Date: Sun Jun 07 2009 - 02:12:20 EST


Chris Friesen wrote:
Avi Kivity wrote:

I am selling virtual private servers. A 10% cpu share costs $x/month, and I guarantee you'll get that 10%, or your money back. On the other hand, I want to limit cpu usage to that 10% (maybe a little more) so people don't buy 10% shares and use 100% on my underutilized servers. If they want 100%, let them pay for 100%.

What about taking a page from the networking folks and specifying cpu
like a networking SLA?

Something like "group A is guaranteed X percent (or share) of the cpu,
but it is allowed to burst up to Y percent for Z milliseconds"

If a rule of this form was the first-class citizen, it would provide
both guarantees, limits, and flexible behaviour.

I think you're introducing a new control (guarantees, limits, burst limit), but I like it.

--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

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