How to tell if Trim and/or GC is working?

This may sound like a basic question, but how can I tell if TRIM or GC is working on my 480G Sandisk Extreme. The Sandisk Toolkit indicates that this is enabled, but how can you tell if it happens or what do you have to do to make it occur?

Thanks for any help

As you are using Sandisk toolkit, Ia ssume you are running Windows. On Windows 7 you can chek it by open a command line windows (cmd.exe) and enter the command 

fsutil behavior query DisableDeleteNotify 

If it outputs “0” TRIM commands are sent to the device - whether or not the commands are interpreted correctly by the device can not be tested (don’t know a way - may be there is an SMARt value that can be used as indicator?).

Thanks and I am running W7 X64. Tried the command line and got a “0”. I guess it is working but wish there was a way to tell.