Re: External USB2 HDD affects speed hda

[Lennart Sorensen]

On Thu, Jun 02, 2005 at 03:11:12PM +0200, Rene Herman wrote:
> Many thanks for trying but our systems really are quite different. I'm 
> on an old fashioned north/south-bridge system, where everything does 
> compete for bus bandwidth but on newer systems it's all some form of 
> "hub architecture" (intel nomenclature) or whatever nVidia calls it. I'm 
> not too familiar with it, but I do believe that on that system one 
> needn't really expect a misbehaving EHCI controller to have (much?) 
> effect on IDE throughput.
> 
> Would you be willing to enable CONFIG_USB_DEBUG and then look at 
> /sys/class/usb_host/usbN/registers, for usbN your EHCI bus (the second 
> line of that file will say EHCI for that one)? Example for me:

I will try and do that when I get a chance.  I can also try it on a
machine with an add in ehci card (Via KT133 chipset + NEC ehci card).

> bus pci, device 0000:00:09.2 (driver 10 Dec 2004)
> EHCI 1.00, hcd state 1
> structural params 0x00002204
> capability params 0x00006872
> status 0008 FLR
> command 010009 (park)=0 ithresh=1 period=256 RUN
> intrenable 37 IAA FATAL PCD ERR INT
> uframe 2dee
> port 1 status 001000 POWER sig=se0
> port 2 status 001000 POWER sig=se0
> port 3 status 001000 POWER sig=se0
> port 4 status 001000 POWER sig=se0
> irq normal 0 err 0 reclaim 0 (lost 0)
> complete 0 unlink 0
> 
> When my IDE throughput is normal, the "status" line is always as above, 
> but after switching on the USB2 HDD (and even after switching if off 
> again and/or unplugging it) "Async" and/or "Recl" start toggling on and 
> off (and IDE throughput drops) until I rmmod ehci-hcd. You'd need to 
> check the file a few times in a row...
> 
> In fact, anyone who could do the same would be much welcome. Certainly 
> with the EHCI controller on a PCI card, and even more certainly with a 
> VIA VT6212 EHCI controller on a PCI card.

> Your 41MB/s for the SATA disk on nForce2 does seem a bit low. The 50 
> here is with a PATA Maxtor 120G on a UDMA66 controller. I just checked 
> and I see that with current kernels hdparm -a hasn't as much influence 
> as it used to have on the hdparm -t result, but try after a "hdparm -a N 
> /dev/sda" (sda for SATA, right?) for at least N = 256, 512, 1024, 2048 
> and 4096...

Well the SATA is using an Sil3112A controller.  Not sure how fast they
are.

The system also isn't entirely idle, so who knows what might affect the
speed.  I only get 30M/s at the moment on the same type of WD 120G SATA
drive on an ICH5R chipset, although I am pretty sure I have got more
than that when it was idle before.

Len Sorensen
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