Re: [RFC PATCH] x86 alternatives : fix LOCK_PREFIX race with preemptiblekernel and CPU hotplug

From: Jeremy Fitzhardinge
Date: Wed Aug 13 2008 - 23:36:20 EST


Mathieu Desnoyers wrote:
A virtualized guest kernel could use that to limit its use of the
overall machine CPU resources in different time periods. Policies can
determine how many physical CPU a virtual machine can be tied to, and
that may change depending on e.g. the workload or time of day. Having
the ability to efficiently switch to UP for a long period of time seems
important in this use-case.

Not very convinced. Unplugging cpus is a pretty coarse way to control resource use. There are lots of other mechanisms. And it's not like an uncontended lock is all that expensive these days...

J

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