Fedora Users — Re: hdparm shows poor performance on cached reads for PATA drive

John Summerfield wrote:

Konstantin Svist wrote:
Konstantin Svist wrote:
I have an older laptop (HP ze4400 series) with a PATA hard drive.
When I check hdparm -T /dev/sda in Fedora 7 or 8, it shows meperformance of ~180MB/sec
When I use a boot CD (gparted/clonezilla) to check the speed (by theway, it uses the old style /dev/hdc, instead) - it tells me theperformance is upward of 400MB/sec
The buffered speed seems about the same in either case at ~30MB/sec.(I've tried enabling/disabling various settings via hdparm, while inboot CD mode)
Why is this happening and is there a way to fix it (withoutreverting to /dev/hdc)?
*bump* since I got no replies from last time
Just ran another test: in F8, I get 123MB/s on cached reads, 28.55MBon buffered reads. When booted into Knoppix 5.1.0, cached reads say210MB/s, and buffered reads fluctuate between 15MB/s and 20MB/s.
For general performance, cached performance is pretty irrelevant,you're still constrained to the bus speed at best, and the generalability of the hardware (ATA motherboard electronics included) ingeneral.
I don't have the foggiest idea of what an HP ze4400 is; depending onits age your speed of 28.55MB is pretty good.

I agree that cached performance doesn't matter all that much, normally.However, it's a pretty large drop in performance - and I'm trying tofigure out why it happened. I wouldn't be worried about it if it wereoff 5-10% - but it's just about HALF of the old value.Also (and I'm not sure about this...) this might indicate some problemwith latency (which *would* be pretty important, especially if it's thismuch).