[ofw] MTHCA registry parameters

[Erez Cohen]

Please see below


________________________________

From: ofw-bounces at lists.openfabrics.org
[mailto:ofw-bounces at lists.openfabrics.org] On Behalf Of Fab Tillier
Sent: Wednesday, April 11, 2007 10:14 PM
To: ofw at lists.openfabrics.org
Cc: Jeff Baxter; Xavier Pillons
Subject: [ofw] MTHCA registry parameters


Hi folks,
 
What do the following registry parameters for MTHCA do?
 
HKR,"Parameters","TunePci",%REG_DWORD%,0
-          What does PCI tuning do?
[Erez Cohen] It has different actions for PCIX and PCIe based HCAs
            PCIX: Change default value of "max receive byte count" in
PCI configuration header
            PCIe: Change default value of "max read request size" in PCI
configuration header
 
-          Why is it off by default?
[Erez Cohen] We seen the need for this configuration only on some
systems (chipsets) 
-          Does turning it on result in higher bandwidth or lower
latency?
[Erez Cohen] BW only 
-          What are the risks in turning it on?
[Erez Cohen] reduce BW in some systems.  
 
HKR,"Parameters","ProcessorAffinity",%REG_DWORD%,0
-          Is this ISR or DPC affinity, or both?
-          Does this apply to kernel mode only?
 
HKR,"Parameters","MaxDpcTimeUs",%REG_DWORD%,10000
-          What does this do?
-          How does it affect performance when the value is increased or
lowered?
-          Is this default value tuned for performance or system
responsiveness?
 
Thanks!
-Fab
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