usb 3.0 half speed with pci=nomsi

Skunk Worx skunkworx at verizon.net
Sun Aug 19 22:39:47 UTC 2012


On 08/18/2012 01:38 PM, Skunk Worx wrote:
> Hi,
>
> I have two similar linux machines with legacy PCI / USB 3.0 cards
> plugged in. These use the NEC uPD720200 USB 3.0 Host Controller and the
> xhci module.
>
<snip>
>
> Is it likely that the kernel option is what's dropping the USB 3.0
> performance to about 1/2 speed?
>

Solved, replying for completion. The supposed USB 3.0 extension cable 
was dropping the speed. Going direct to the port raised the speed to 
about 85 MB/sec.

---
John



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