So does the warning about using this kernel update on with systems that
have a certain VM PTF installed only apply to using the spin_retry
parameter?
Alan Altmark wrote:
On Friday, 07/21/2006 at 08:23 EST, Rich Smrcina <[EMAIL PROTECTED]>
wrote:
spin_retry Kernel parameter
With this update an additional kernel-command line parameter is
provided. The default value is 0 for this parameter. Setting this
parameter to 1000 has shown for most workloads on a linux runnig under
z/VM that the number of DIAG 44 calls is significant reduced.
Is this only related to multiple virtual CPUs or does it apply to any
workload?
Only multiple virtual CPUs. In a uniprocessor environment Linux shouldn't
issue diag 44.
Has the performance impact of this change been measured? If so, what is
it?
Not a direct answer to your question, but for some information on the
effects of z/VM 5.2 DIAG 44 Fast Path support, see
http://www.vm.ibm.com/perf/reports/zvm/html/diag44.html. When combined
with a reduction in diag 44s, you get a nice (technical term) performance
improvement.
Alan Altmark
z/VM Development
IBM Endicott
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Rich Smrcina
VM Assist, Inc.
Phone: 414-491-6001
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