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From: Nick Bijens on 18 Jun 2010 08:52
Hello,

I have a strange feature on my HP Compaq 8000. I have a device
connected via FireWire. While data is transferred from device to PC,
throughput is rather low. This is easy to determine using a FireWire
bus analyzer. The analyzer shows a lot of data packets have to be
resend/retried. However, when I insert a USB flash drive, my FireWire
performance goes up: the analyzer shows no retries any longer. I used
several USB sticks and only one had no impact. Using a USB mouse
doesn't have influence either.

What can be the cause for this?

The PC has no specials installed: it's the default XP OS that comes
with the PC and of course a small application that initiates the data
transfers.

Thank you.
From: Pavel A. on 18 Jun 2010 12:02
It could be too aggressive power management of the platform and
lack of coordination with 1394 controller.
When the CPU and memory controller go to C3, the DMA latency
becomes too bad.
OTOH, high-speed USB traffic prevents going to C3+.

Does the BIOS allow disabling C3 or higher states (or whatever power saving
super duper buzzword Intel calls it) ?
Is your unhelpful USB stick 1.1 ?

-- pa


"Nick Bijens" <dominique.bijnens(a)gmail.com> wrote in message
news:5036ca18-c3fd-4060-a5e4-5986522a3449(a)x27g2000yqb.googlegroups.com...
> Hello,
>
> I have a strange feature on my HP Compaq 8000. I have a device
> connected via FireWire. While data is transferred from device to PC,
> throughput is rather low. This is easy to determine using a FireWire
> bus analyzer. The analyzer shows a lot of data packets have to be
> resend/retried. However, when I insert a USB flash drive, my FireWire
> performance goes up: the analyzer shows no retries any longer. I used
> several USB sticks and only one had no impact. Using a USB mouse
> doesn't have influence either.
>
> What can be the cause for this?
>
> The PC has no specials installed: it's the default XP OS that comes
> with the PC and of course a small application that initiates the data
> transfers.
>
> Thank you.

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