LSI 7202CP User Manual
Page 29
BIOS Features
3-11
Copyright © 2001, 2002 by LSI Logic Corporation. All rights reserved.
WWN 2100002037105212 Port ID 1
Target 3
Unit 0
Disk
SEAGATE ST39173FC
6258
WWN 2100002037103da8 Port ID 26
Target 4
Unit 0
Disk
SEAGATE ST39173FC
6258
WWN 210000203710324a Port ID 73
3.1.5.5 Interrupt Coalescing
Interrupt coalescing allows the firmware on the Fusion-MPT device to
group I/Os together to minimize the overhead to the host system. This
feature can result in significant performance benefits when I/Os are
rapidly coming into the adapter, as is the case while performing small
sequential reads from a disk.
LSI Logic has performed significant testing under multiple I/O conditions,
and has determined that the interrupt coalescence values that are
beneficial over a wide range of I/O conditions are a depth of 4, with a
timeout of 160 microseconds. This means that the host is interrupted
only once for four I/Os processed by the chip, unless 160 microseconds
has passed since the host was last interrupted.
Although LSI Logic has determined that these settings are optimal for a
wide variety of situations, your own I/O load may benefit from a deeper
queue or a longer timeout. LSI Logic provides a mechanism to modify
these values and write them to the nonvolatile EEPROM on the adapter.
Select the port or adapter shown (use the port name your system assigns):
ok select /pci@8,700000/IntraServer,fc@1
ok show-interrupt-coalescing
Interrupt coalescing timeout is a0 (160 decimal) microseconds
Interrupt coalescing depth is 4 (4 decimal)
ok set-interrupt-coalescing
<- command with no arguments prints help
usage is <timeout><depth> set-interrupt-coalescing
ok 100 8 set-interrupt-coalescing
Interrupt coalescing timeout selected is 100 (256 decimal) microseconds
Interrupt coalescing depth selected is 8 (8 decimal)