Messages in this thread | | | Subject | Re: is minimum udelay() not respected in preemptible SMP kernel-2.6.23? | From | Peter Zijlstra <> | Date | Thu, 08 Nov 2007 10:11:21 +0100 |
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On Wed, 2007-11-07 at 18:20 -0600, Matt Mackall wrote:
> This and other cases > (lots of per_cpu users, IIRC) actually want a migrate_disable() which > is a proper subset.
The disadvantage of migrate_disable() is that it complicates the load-balancer but more importantly, that it does bring a form of latencies with it that are hard to measure. Using preempt_disable() for these current per-cpu users basically forces them to keep it short.
Which is a GOOD (tm) thing.
If we go overboard with this migrate_disable() stuff we can end up with a very hard to analyse system that sporadically does weird stuff.
So, please, don't start that again.
Also see: http://lkml.org/lkml/2007/7/23/338
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