What does "USB selective suspend" mean?

Question

In Windows 7, Power Options->USB Settings->USB selective suspend setting, what does "USB selective suspend" mean?  Also, given that there is only one setting, why does it say "USB Settings" instead of "USB Setting"?

Answer 1

A USB device driver can send a message to windows telling it to idle the device.  This puts the device in a low-power state (the suspend state).  When a USB device is suspended, windows does not wait for it to respond before entering a sleep or hibernate mode.  If you disable this feature, the system will simply return a failure to the driver when the driver attempts to enter suspend state.  If the driver complies with Microsoft guidelines, it will simply retry the idle request at every expiration of its idle timer.

Answer 2

dude, where do you think Google Searches take you?... places like this!; don't waste the space telling people to Google it. You think someone would come here before typing it in Google?!

Answer 3

_Kelter thanks for the explanation... now can I ask for a prediction? 

I'm having problems with Win 7 (Ultra 64) waking up from sleep, similar to lots of queries here, MS support, and the web.  After finding out how to generate a "Power Efficiency Diagnostics Report" I see multiple errors of "USB Suspend:USB Device not Entering Suspend".  Somewhere in my researching this, I found a suggestion that worked for everyone who tried it, which was to go into Device Manager>USB Controllers> and then select the first item (in my case it's "Generic USB Hub") open its Properties>Power Management and then DESELECT "Allow the computer to turn off this device..."  and then the suggestion was to do this for EVERY USB device in the list.(!!!)

So here's the question, do you think that going to Power Options->USB Settings->USB selective suspend and then DISABLING it would have the same effect as what was described above?

Answer 4

Disabling the USB selective suspend has worked for me thus far.  I manage a computer lab and 5% to 7% of the systems have had power-up issues.  Thx.

Answer 5

In other words...you don't know.