Bartlomiej Zolnierkiewicz wrote:
On 1/13/06, Helmut Toplitzer <[EMAIL PROTECTED]> wrote:
I've got a question about a small experiment I made:
I tried to find out the transfer-rate of my hd by useing
hdparm -t /dev/hda
and got changing transferrates starting from
37MB/s with CPU not utilized
55MB/s with CPU 100% utilized
[ ... ]
22MB/s with ehci-hcd loaded and a device already initilized
55MB/s with ehci-hcd loaded and CPU 100% utilized
(see log1/log2)
As discussed in this thread:
http://marc.theaimsgroup.com/?l=linux-kernel&m=111765523627674&w=2
It seems that the problem is caused by flakey USB chipset
thus IDE folks cannot do much about it, sorry.
Indeed. It seems VIA EHCI controllers are quite simply terminally
broken. And Helmut is also seeing problems with a soundcard.
Helmut, I believe it would be better if you could try the first of these
tests without the VIA USB2 controller even plugged in and then see if
you still get that effect.
(Bartlomiej, note by the way that in my case it's not a VIA southbridge
but an AMD756, although I believe that might be quite similar to old VIA
southbridges in so far as that VIA looked at that one)
So it looks like CPU/USB/IDE is in some interaction. Any
ideas what to do against this. My current kernel is
2.6.15
As said, if you can be bothered, taking the VIA EHCI controller out of
the picture would be interesting. Personally, I only experience the
throughput drop with ehci-loaded and in use or used, fixed by unloading
ehci-hcd so I can't test more than that, but I wouldn't be terribly
surprised if completely taking out the USB controller would solve other
problems as well. As clear by now, that chip is doing some _very_
strange things to the bus.
Rene.
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