All USB inputs on a laptop are not equal (X-Runs)

[English Guy]

I shared this because it might save someone from a lot of tweaking their system when the answer is simple.

I started having a lot of x-runs on my HP laptop with alesisi io2 USB interface, exactly the same setup I had used the night before without issue. I started thinking 'settings,' different kernel etc.

I suddenly realised I had plugged in to the USB socket on the other side of the machine to last night; they are all USB2 so I didn't think there would be any difference. However, when I changed back to the other side the software ran fine again.

So, my conclusion is, on some machines the USB sockets are not equal. Hope this helps someone.

[kbongosmusic]

I believe you are correct, some USB connections are better than others. I think some of it maybe is a daisy chain thing, where USB has 4 or 5 ports and if you want more it gets daisy chained(via a hub). USB ports on the back connections are normally the most direct, sometimes they put a few in front, maybe those are off a built in hub that would give different results. I recall some oddness with even the ones in back, where some on a particular machine were faster than others - seems odd. And definitely usb hubs and cables can be sources of problems. There was some report I saw recently about so many problems with Ebay cheap usb cables that Ebay was taking action to try and force vendors to rate them better. I used to be on the usb-linux mail list and I recall a lot of 'check if it's a problem with a cheap hub or cable type problem' coming up. But it's kinda one of those things you take for granted if it is mostly working. You could investigate and probably learn what ports are on internal hubs, I believe that can be found out with something like lsusb or some usb kernel info. Maybe do some speed/stress testing with flash dongles.

[English Guy]

(snip) You could investigate and probably learn what ports are on internal hubs, I believe that can be found out with something like lsusb or some usb kernel info. Maybe do some speed/stress testing with flash dongles.

I am just happy it works. I thought I would share as it is another of these situations where you could make drastic changes to what is actually a good system and not actually fix anything.

[folderol]

Not only do ports share internal hubs, but those hub may be sharing interrupts too. I always try to have usb audio on the least contested ones, and things like mouse, keyboard etc. on something more congested.
Look at:
lsusb
and:
cat /proc/interrupts

[gimmeapill]

Just like Folderol said.
Another hint: check for the blue one that doubles as USB3. It is the least likely to be going trough an internal hub (even when configured as USB2 only in the BIOS).