Rockbox mail archiveSubject: Re: X5 dual boot
Re: X5 dual boot
From: Jens Arnold <arnold-j_at_t-online.de>
Date: Tue, 02 May 2006 23:56:40 +0200
On 02.05.2006, RaeNye wrote:
>>> (The next totalliy unrelated topic would be DMA for ATA, but
>>> I leave this for later)
>> Yes, ATA DMA might speed things up a little, but not as much
>> as you might
> think. The assembler optimized ATA driver is pretty fast.
> Again I think it's a don't-burden-cpu-for-no-reason thing. DMA
> is there for a reason; let the CPU spend its cycles in SWCODEC
> (or GUI, whatever).
ATA DMA might be equally fast, or even a bit faster,than the asm
optimised transfer routines. I am planning to try that on irver.
However, even with DMA, ATA transfers will still slow down the
CPU unless the CPU is *exclusively* working from cache + IRAM.
SDRAM access is *the* major bottleneck, and CPU and DMA
controller share the same bus. Furthermore, ATA DMA needs
special casing, since one of the IRAM blocks isn't DMA capable.
Received on 2006-05-03