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Operating Systems AIX IBM AIX I/O Performance Tuning Post 303031803 by bakunin on Wednesday 6th of March 2019 03:25:16 AM
Old 03-06-2019
Quote:
Originally Posted by c3rb3rus
I did not modify the hdisk max_transfer size during this test as there was a suggestion made to change max_transfer (which is part of the hdisk) and max_xfer_size which is part of the fc hba - do I change both?
I would not (at least not without imminent pressure to do so) change the "max_transfer" property of the hdisk. If you use disks (that includes virtual disks) AIX (or, rather, the driver it uses) recognizes this is alreay set up fairly. You should change the HBAs property "max_xfer_size", though: optimal values depend on the "environment" of the other components involved so that the driver cannot estimate it.

I have successfully used a value of 0x400000 in a similar surrounding so i'd start in your case with probably a value of 0x800000, test that thoroughly and eventually go back to 0x400000 if it doesn't work out.

I hope this helps.

bakunin

Last edited by bakunin; 03-06-2019 at 05:16 AM..
 

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PMC(1)							    BSD General Commands Manual 						    PMC(1)

NAME
pmc -- performance-monitoring counter interface for command execution SYNOPSIS
pmc -h pmc -C pmc -c event command [options ...] DESCRIPTION
pmc is a means of using a processor's performance-monitoring counter (PMC) facility to measure various aspects of a program's execution. It is meant to be used in a fashion similar to time(1). The arguments are as follows: -h Display a list of performance counter events available on the system. -C Cancel any performance counters that are currently running. -c event Count the event specified by event while running the command. DIAGNOSTICS
PMC support is not compiled into the kernel Performance-monitoring counter support has not been compiled into the kernel. It may be included using the PERFCTRS option. See options(4) for details. PMC counters are not supported by CPU Performance-monitoring counters are not available for the CPU. SEE ALSO
time(1), options(4) HISTORY
The pmc command first appeared in NetBSD 1.6. AUTHORS
The pmc command was written by Frank van der Linden <fvdl@wasabisystems.com>. The kernel support for reading performance counters on the i386 architecture was written by Jason R. Thorpe <thorpej@zembu.com>. BUGS
The pmc command currently only supports performance-monitoring counters on the i386 architecture. BSD
October 24, 2000 BSD
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