AmigaOne DMA Problem

[Piru]

for a machine intended to run just one OS that is specifically designed for it the ArticiaS works okay.

Marvell is over 100% faster with HD DMA than ArticiaS. Same southbridge, same HD.

I am no expert, but to me it seems as if Articia was seriously crippled.

[Piru]

@DrBombcrater

I fail to see how you can state this with any authority.

Pegasos1 (ArticiaS) vs Pegasos2 (Marvell). Under Linux and MorphOS. Pegasos1 transfers about 36-37MB/s, whereas Pegasos2 transfers 88-89MB/sec.

As far as I understand AmigaONE delivers same speed as Pegasos1 (at least Linux), albeit with possibility of errors. Correct me if I am wrong.

[EDIT]added some speed figures for reference[/EDIT]

[Piru]

@mikeymike

Transfers from what to what?

HD to memory, raw same sector read.
HD is Seagate ST3120026A 120GB.

And of what exactly...

SCSIBench V1.0
Transfer Size: 256 k
Transfer Type: Same Sector

These settings benchmark the transfer speed off the disk cache, not continuous disk transfer speed. Thus, the IDE bus is benchmarked.

My PC (UDMA100) could probably at best burst at ~40MB/sec, and that's if it had a second identical disk in, and probably on the same IDE chain, and if the both disks were defragged and the file(s) were huge (like 100MB+ each). Normally though I'd expect 20 - 30MB/sec for the conditions I've just stated.

Benchmark utilities on my disk suggest ~35MB/sec best throughput. Internal disk transfer synthetic benchmarks (which IMO are by no means practically true) suggest ~300MB/sec.

We're interested about the IDE bus performance, not about particular disk performance. BTW my ST3120026A does 54 MB/s sequental access (Peg2).

I don't think there's an IDE disk that can even do 90MB/sec transfer speed to a destination that isn't the same disk, currently available at the moment, let alone if it were in a Peg1/2.

Well you think wrong then. When we're comparing IDE DMA (peak) performance we want to compare readspeed from cache.

Peg2 + ST3120026A does close to 90MB/s.

PS. CPU Usage is 97% because I run distributed.net client on the background. CPU Usage is around 13% without it
[EDIT] SCSIBench's internal CPU Usage meter seems 'slightly' broken, it reports 70% CPU Usage. [/EDIT].

PPS. This is not supposed to mean that I claim I get 90MB/s generic performance. This is not the case, I'm trying to compare peak performance, which with ATA-100 limits to theoretical 100MB/s.

[EDIT] Added some clarifications [/EDIT]

[Piru]

@DrBombcrater

A Pegasos is not an AmigaOne.

I didn't claim that. I suggested that to my knowlege AmigaONE IDE (peak bus-) performance is identical (or close) to Pegasos1 one.

With a 40GB Maxtor +8 drive my own A1 has hit 60MB/sec transfer speed (physical transfers from disk, not cache) under Linux.

Wow. That's nice.

May I ask how you benchmarked this?

[EDIT] Some rewording to deliver the idea better [/EDIT]

[Piru]

@mikeymike

Now hold your horses. I am not attempting to benchmark my harddisk, or compare this harddisk to any other harddisk. Nor am I claiming 90MB/sec practical speed.

I am speaking of the interface speed, the absolute maximum speed the drive can deliver data from the cache to host system. I am trying to find the maximum speed possible thru the IDE interface. For that, reading 256k buffer repeatedly seems best generic test (sizes 128k and 512k are quite close too, but as fast as 256k).

May I remind you the peg1 and peg2 systems were identical, except motherboard (northbridge), CPU and memory. Same NIC, same gfxcard, same southbridge, same harddisk.

Peg1 does 36-37 MB/s, whereas peg2 does 88-89MB/s, same environment, same testprogram, same parameters.

I'm sorry to upset you.


[EDIT] Indeed, as someone was kind enough to point out, the cpu indeed is different too. That probably explains some of the difference in speed, aswell. :-) [/EDIT]

[Piru]

@DrBombcrater

Ah great. Mind pasting the hdparm command used and command output? I'd like to reproduce the test.

[Piru]

@mikeymike

I've gone OT, which I apologize for. I mainly compared peg1 G3 and Peg2 G4, while also suggesting that I believe A1 (with same CPU config) is closer to Peg1 than Peg2.

This isn't exactly on topic, again sorry about that.

But, it's a pointless statistic.

Mostly yes. However, if the peak performance is capped by the northbridge it's quite serious. I believe this to be the case with ArticiaS.

The possibility that you were just blowing the Peg's trumpet

Let me assure you this was not my intention.

Some guy who does a decent benchmark on an A1 with OS4 or Linux is going to get extremely differing results from yours through no fault of their own, and potentially no failing or issue with the hardware, is likely to be pointing at the wrong factor as the cause of the 'problem'.

Valid point. I probably should have pointed out that SCSIBench and hdparm results are not comparable.

In a practical disk throughput test, ie. a few hundred megs of data from one device to another storage device, your Peg2 cannot do anywhere near 90MB/sec.

Which I never claimed. I wanted to test the max peak performance of the IDE implementation.