hdparm shows poor performance on cached reads for PATA drive

[John Summerfield]

Konstantin Svist wrote:

>>
>> For general performance, cached performance is pretty irrelevant, 
>> you're still constrained to the bus speed at best, and the general 
>> ability of the hardware (ATA motherboard electronics included) in 
>> general.
>>
>> I don't have the foggiest idea of what an HP ze4400 is; depending on 
>> its 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 to 
> figure out why it happened. I wouldn't be worried about it if it were 
> off 5-10% - but it's just about HALF of the old value.
> Also (and I'm not sure about this...) this might indicate some problem 
> with latency (which *would* be pretty important, especially if it's this 
> much).

Latency a problem on a laptop?

One of the tradeoffs one accepts in choosing a laptop is that it's 
performance is going to be less than on less portable systems.

For starters, disks mostly spin at 5400 rpm instead of the usual 7200 on 
desktops and 10,000-15,000 on other systems.

Latency might be important in systems doing lots of short reads; then 
seek time matters too. When loading multimegabyte programs and data 
files into RAM so they can be paged out, forget it.




-- 

Cheers
John

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