Performance enhancements & Disk Access

Tom Adelstein adelste at yahoo.com
Mon May 9 21:14:43 UTC 2005


This is a follow up to a DMA question and I must have deleted the email.

The topic effects the use of hdparm


The effects of various hdparm commands.

[root at dvalin root]# hdparm -t /dev/hda

/dev/hda:
Timing buffered disk reads: 64 MB in 2.97 seconds = 21.54 MB/sec
[root at dvalin root]# # Now let's switch to 32-bit I/O
[root at dvalin root]# hdparm -c 1 /dev/hda

/dev/hda:
setting 32-bit I/O support flag to 1
I/O support = 1 (32-bit)
[root at dvalin root]# hdparm -t /dev/hda

/dev/hda:
Timing buffered disk reads: 64 MB in 2.97 seconds = 21.56 MB/sec
[root at dvalin root]# # See? A slight improvement
[root at dvalin root]# # Now let's turn off DMA and see how bad things
get. . .
[root at dvalin root]# hdparm -d 0 /dev/hda

/dev/hda:
setting using_dma to 0 (off)
using_dma = 0 (off)
[root at dvalin root]# hdparm -t /dev/hda

/dev/hda:
Timing buffered disk reads: 64 MB in 10.94 seconds = 5.85 MB/sec






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