USB mouse lag through hub


R

Rauschman

I have a Logitech G5 mouse that works wonderfully when plugged into a
usb port on my Sony Vaio laptop. I just bought a new D-Link 7 port
high speed hub, and when I connect my mouse through the hub, the mouse
slows down and becomes jerky at times. I can understand the slowdown
somewhat, but I have the SetPoint software set at 200Hz. The keyboard
and iPod and printer all work fine off the hub. Whenever I click
something or scroll, the mouse freezes for about a second and then
continues to function. If I click while it is frozen, it will not
register the click when it starts responding, so this is not norml lag
it seems.

Any suggestions?
 
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R

Rauschman

Forgot to mention that even when the mouse is the only device
connected to the hub, it locks up just as it does with other devices
connected. I've tried changing ports on the hub and changing which
port on the laptop the hub uses. Nothing speeds it up.
 
R

R. McCarty

Even though USB devices can be daisy-chained up to a depth of
128 devices you've encountered a common issue. The USB Hub
and it's controller have limited Bandwidth and Power. If you check
you may find that you're at or near one of those limitations.

I frequently have to add an additional PCI expansion USB card
to PCs so that high demand devices can have adequate resources
and not have to share with other peripherals.

For your situation I'd recommend a PC Card or PCExpress USB
card to host your mouse and avoid Hubs for high demand devices.
 
A

AlexB

In addition to what R. McCarty said I want to add that you can use a USB hub
for: (a) printer, (b) a photo printer, (3) fax (input and output), etc.

Those processes are easily broken into manageable packages and the delivery
of the next package can be delayed until the channel is available. Until
then the job will wait in a queue. You do not notice the limitation because
you do other things and then go to your printer to pick up a few pages. You
do not even care if it was done pretty much in the way your hub handles your
mouse.
 
R

Rauschman

I'm guessing that the hub just can't supply enough power, even with
only the mouse plugged in and the hub powered. Do you think I would
notice a significant data rate drop if I use my external hard drive on
the hub instead of the mouse?
 
R

R. McCarty

Best to setup and then use Device Manager to check loading:
USB Root Hub, Power ( TAB ) to see power consumption
Controller, Advanced (TAB) for bandwidth usage
Since the default view of Device Manager makes it hard to tell
which controller serves which hub you can use a tool from MS
called USB Device Viewer that shows the association graphically.
Sorry I don't have the link for download.

External drives can be a problem on a Hub since other USB
devices will significantly affect the throughput which usually will
max out at ~22-25 Meg-per-Sec.
 
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A

AlexB

USB Device Viewer is one of the APIs in the Windows Driver Kit Tools.

WDTK is a massive image file that can be downloaded from MS sites for free.

Then you have to open it in a "3-rd party" software.

It does have usbView.exe in it, the one you are talking about. MS sites
mention some problems with it. Also it was Windows 98 file and it is
unlikely that it has been updated for new OSs.

I think all this high science is not needed for the OP. He has to find his
answers thru trial and error. He has to understand that the USB devices are
very convenient but have inherent limitations. He has to accept them.

Answering his question, YES, it is a good idea to use an external HDD as a
storage device and connect it to the machine via a USB hub.

It is very important to use a USB hub that has its own power supply. It will
work much better. There are some that do not have PSU. They are just toys.
 
D

Dwarf

Hi Rauschman,

There are somethings which will work correctly when plugged into a hub and
somethings which don't. I recommend that mice and keyboards are connected
directly to your machine and not through a hub. Other items such as printers,
external drives etc should work satisfactory. The reason for this is
'Polling'. For example, a USB port is set to scan for attached devices every
few milliseconds to find out whether there is anything attached to that port.
This works fine when there is only one device connected to the port. When you
have a hub connected, things change. Each time the USB port on your machine
performs a scan, a different port on your hub is accessed. This works fine
for things such as printers. However, for things such as mice which are in
constant use, this can introduce delays and it is these delays or pauses that
are causing your problem. The reason why it does not register a click when
the mouse is frozen is that the system is unable to 'see' the mouse at that
instance in time and is therefore unable to ascertain its status at that
point.
Dwarf
 
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R

Rauschman

Hi Rauschman,

There are somethings which will work correctly when plugged into a hub and
somethings which don't. I recommend that mice and keyboards are connected
directly to your machine and not through a hub. Other items such as printers,
external drives etc should work satisfactory. The reason for this is
'Polling'. For example, a USB port is set to scan for attached devices every
few milliseconds to find out whether there is anything attached to that port.
This works fine when there is only one device connected to the port. When you
have a hub connected, things change. Each time the USB port on your machine
performs a scan, a different port on your hub is accessed. This works fine
for things such as printers. However, for things such as mice which are in
constant use, this can introduce delays and it is these delays or pauses that
are causing your problem. The reason why it does not register a click when
the mouse is frozen is that the system is unable to 'see' the mouse at that
instance in time and is therefore unable to ascertain its status at that
point.
Dwarf

I ended up returning the hub. Even if the mouse was the only item
connected to the hub, my cursor still jumped. Turns out that the AC
powered hub does not deliver full voltage to each port. Thus, the
mouse was not receiving enough power to run smoothly. I'm still
looking for a fully powered 7+ port USB2.0 hub for a decent price.
 

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