Re: [Linux-ia64] Pre-emption patch for IA-64

[David Mosberger <davidm@napali.hpl.hp.com>]

Peter Chubb has been working on adding preemption support to 2.5.  I
applied his patch in the 2.5.64 patch.  I'm sure he would appreciate
more people beating on it.

	--david

>>>>> On Fri, 14 Mar 2003 11:21:21 -0600, Mario Smarduch <cms063@email.mot.com> said:

  Mario> Hi, we're trying to build a reliable low-latency system for
  Mario> use in telco call processing carrier grade environments (on
  Mario> rx2600 NEBS like servers) . One of the patches we're heavily
  Mario> relying on is the 'Kernel Preemption' patch. First of we're
  Mario> interested in the (i) status of this patch on IA-64 (ii) any
  Mario> issues that you may have ran into.

  Mario> Our understanding is that the 'Preemption Patch' offers a
  Mario> systematic scheduling checkpoint vs. 'low latency patch'
  Mario> which examines the kernel for any long running code and based
  Mario> on that preemption checks are inserted in the kernel proper
  Mario> only (kernel.org) but addon packages may introduce long
  Mario> latencies. While we plan to run with 1mS clock tick, low
  Mario> latency and the preemption paches, the preemption patch is
  Mario> viewed as a must to gurantee a bound on 'soft-realtime
  Mario> response'.  Please point out if these assumption are somewhat
  Mario> correct or is too much emphasis being placed on the
  Mario> preemption patch, the soft-realtime response we're looking
  Mario> for is 1mS.