DMA transfer vs Programmed I/O on an A2000?

[desantii]

I was testing an Oktagon 2008 board in my A2000, wanted to see how fast it was comapred to a GVP 8mb ram/scsi board.  What does the below mean?
 
does not use DMA but interrupt driven programmed I/O - From Amiga.Resource
 
Testing the board its actually seems quite fast 2.6mb/s reads in sysinfo vs. 1.3 mb/s for the GVP board. The SCSI in tmy 030 GVP accel shows 2.2mb/s so its even faster than this one?
 
thanks

[Damion]

Basically, the CPU is used for the data transfers, as opposed to a processor on the SCSI board.

As far as a Z2 card goes, there's not going to be much difference in performance when it comes to raw transfer rate. Multitasking would be nicer with a DMA card, though, since the CPU is mostly free while the transfers occur.

To get a better idea, try this benchmark on both and compare the results.

[ChaosLord]

You should always use DMA.

[desantii]

I did use that benchmark as well, same speeds though
 

Basically, the CPU is used for the data transfers, as opposed to a processor on the SCSI board.
 
As far as a Z2 card goes, there's not going to be much difference in performance when it comes to raw transfer rate. Multitasking would be nicer with a DMA card, though, since the CPU is mostly free while the transfers occur.
 
To get a better idea, try this benchmark on both and compare the results.