Dell PowerConnect Brocade 825 Brocade Adapters Troubleshooting Guide - Page 139

OS tunable parameters - brocade 825 driver

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Tuning storage drivers 4 • Interrupt delay Default: - 1125 microseconds on the Brocade 415, 425, 815, 825, and 1860 - 25 microseconds on the Brocade 804, 1007, 1010, 1020, and 1741 Valid Range: 0 through 1125 microseconds Note that the value of 0 disables the delay timeout interrupt. • Interrupt latency Default: - 225 microseconds on the Brocade 415, 425, 815, 825, and 1860 - 5 microseconds on the Brocade 804, 1007, 1010, 1020, and 1741 Valid Range: 0 through 225 microseconds Note that the value of 0 disables the latency monitor timeout interrupt. • Interrupt Coalescing When this feature is turned off, I/O completion requests are not coalesced by the firmware. While this helps reduce I/O latency, the host CPU will frequently be interrupted, leading to a slower system response under heavy I/O load (more than 7000 I/Os per second). When this feature is turned on, the adapter will not interrupt the host until Interrupt delay duration. Interrupt delay, together with Interrupt latency, helps to reduce the number of interrupts that the host CPU processes per second, leading to improved overall CPU utilization. However, if the number of interrupts handled between the Interrupt delay period is relatively smaller, then this will result in performance degradation as the I/O completion process has slowed down. The BCU vhba command can be used to configure these interrupt attributes for the desired port. vhba --intr pcifn {on | off} [ ] Message signaled interrupts (MSI-X) All Brocade adapters support MSI-X, an eXtended version of the MSI defined in PCI 3.0 specification. MSI-X helps improve overall system performance by contributing to lower interrupt latency and improved host CPU utilization. MSI-X is supported in Windows Vista and Windows Server 2008. To enable MSI-X, set the following registry key value to 0. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\bfad\Parameters\Device\msix_ disable OS tunable parameters Please see the section "Storage Stack Drivers" in Disk Subsystem Performance Analysis for Windows Server 2003 optimizations located on the following website. http://download.microsoft.com Please see the sections "Performance Tuning for Storage Subsystem" and "I/O Priorities" in Performance Tuning Guidelines for Windows Server 2008 located on the following website. http://www.microsoft.com Brocade Adapters Troubleshooting Guide 115 53-1002145-01

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Brocade Adapters Troubleshooting Guide
115
53-1002145-01
Tuning storage drivers
4
•
Interrupt delay
Default:
-
1125 microseconds on the Brocade 415, 425, 815, 825, and 1860
-
25 microseconds on the Brocade 804, 1007, 1010, 1020, and 1741
Valid Range: 0 through 1125 microseconds
Note that the value of 0 disables the delay timeout interrupt.
•
Interrupt latency
Default:
-
225 microseconds on the Brocade 415, 425, 815, 825, and 1860
-
5 microseconds on the Brocade 804, 1007, 1010, 1020, and 1741
Valid Range: 0 through 225 microseconds
Note that the value of 0 disables the latency monitor timeout interrupt.
•
Interrupt Coalescing
When this feature is turned off, I/O completion requests are not coalesced by the firmware.
While this helps reduce I/O latency, the host CPU will frequently be interrupted, leading to a
slower system response under heavy I/O load (more than 7000 I/Os per second).
When this feature is turned on, the adapter will not interrupt the host until
Interrupt delay
duration.
Interrupt delay
, together with
Interrupt latency
, helps to reduce the number of
interrupts that the host CPU processes per second, leading to improved overall CPU utilization.
However, if the number of interrupts handled between the
Interrupt delay
period is relatively
smaller, then this will result in performance degradation as the I/O completion process has
slowed down.
The BCU
vhba
command can be used to configure these interrupt attributes for the desired
port.
vhba --intr pcifn <-c> {on | off} [<Latency> <Delay>]
Message signaled interrupts (MSI-X)
All Brocade adapters support MSI-X, an eXtended version of the MSI defined in PCI 3.0
specification. MSI-X helps improve overall system performance by contributing to lower interrupt
latency and improved host CPU utilization.
MSI-X is supported in Windows Vista and Windows Server 2008.
To enable MSI-X, set the following registry key value to 0.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\bfad\Parameters\Device\msix_
disable
OS tunable parameters
Please see the section “Storage Stack Drivers” in
Disk Subsystem Performance Analysis for
Windows Server 2003 optimizations
located on the following website.
Please see the sections “Performance Tuning for Storage Subsystem” and “I/O Priorities” in
Performance Tuning Guidelines for Windows Server 2008
located on the following website.