Re: ext2/3 performance regression in 2.6 vs 2.4 for small interl

[John Bradford]

Quote from Giuliano Pochini <pochini@xxxxxxxx>:
> 
> On 12-Feb-2004 Andrea Arcangeli wrote:
> 
> > the main difference is that 2.4 isn't in function of time, it's in
> > function of requests, no matter how long it takes to write a request,
> > so it's potentially optimizing slow devices when you don't care about
> > latency (deadline can be tuned for each dev via
> > /sys/block/*/queue/iosched/).
> 
> IMHO it's the opposite. Transfer speed * seek time of some
> slow devices is lower than fast devices. For example:
> 
> Hard disk  raw speed= 40MB/s   seek time =  8ms
> MO/ZIP     raw speed=  3MB/s   seek time = 25ms
> 
> One seek of HD costs about 320KB, while on a slow drive it's
> only 75KB.

Hmmm, but I would imagine that most hard disks have much larger caches
than are popular on removable cartridge drives...

John.
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