Alexander Dalloz wrote:
Am Fr, den 23.01.2004 schrieb Robert D. Arendt um 19:18:
Steve Saady wrote:
I have a Promise Ultra 66 eide controller, but think it is only being
acessed at 33 Mhz. I have looked around, but have not found how to
ascertain what rate Fedora is using it at.
Is there a way to configure FC1 to use it at 66MHz?
<snip>
dmesg|more :
ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx
I added idebus=66 to /etc/grub.conf, so my boot line now looks like:
kernel /vmlinuz-2.6.1-1.53smp ro root=LABEL=/ apm=off idebus=66
should work with the nominal FC1 kernel as well. Really boosted my
disk I/O speed.
Hope this helps,
-Bob Arendt
What kind of hardware are you running - no PC ware or even very old EISA
bus hardware?
idebus=66 is nonsense and might even be dangerous on normal PC hardware,
as simply the bus frequency is 33 MHz and nothing else!
How did you measure the speed boost? Please compare the speed at
idebus=33 and with your setting of idebus=66 and post your values and
how you measured the I/O speed values.
Alexander
Alexander - you're right, I'm wrong.
Hardware: ASUS P4P800 motherboard (865PE+ICH5), 512 Mbyte RAM, 3.0G P4
hda: WDC WD800JB-00ETA0, ATA DISK drive
I used a bash scriptlet to write 1 Gbyte files to the test disk
rm junk*
for n in 1 2 3 4 ; do time dd if=/dev/zero of=junk$n bs=8192K count=128; done
The first time is quicker, due to the OS using available RAM as cache.
Subsequent files should get the sustained write speed. I tried repeating
my tests in single-user boot, and got 20.0 sec/Gbyte, *regardless* of
idebus= setting. Now I believe the idebus parameter is irrelevant,
since the drive is using the udma5 mode, not a PIO mode.
First time I tried this, I saw 30 sec vs. 21 sec; There must have been
some background activity that skewed results; I should have been more
careful.
-Bob Arendt
