Hi everyone!
One of the issues we're looking at for the 1.5 release is whether we can do anything about USB dropouts on the PC.
Microsoft has released a tool (for XP SP2 and above) that examines the low level interrupt calls that go on all the time in Windows - every piece of hardware on a PC requires drivers, and these drivers all use interrupts to do their work. If a driver is well written, then it will take less than a couple of hundred microseconds to run, and this won't affect Scratch LIVE. If the driver is poorly written then it may take up to 2 milliseconds (or more) to run, and this will definately cause USB dropouts when you have the USB buffer set to a low value (e.g. 1 or 2 milliseconds).
We'd like you help to us by running Microsoft's tool and then uploading the results from your PCs to the website.
The tool "RATT" can be found here:
www.microsoft.com
We'd also like to know what the minimum safe USB buffer size for your hardware - for example if you get dropouts at 3ms and below, but not at 4ms, then tell us that the "Minimum Safe Scratch LIVE Buffer Size" is 4ms.
Please download and install RATT, then perform the following steps
Part 1 - Delete the old logs
1) From the RATT system tray icon menu, turn off "Loop Mode"
2) Choose "Stop Monitoring"
3) Open the directrory "C:\WINDOWS\system32\LogFiles\RATTV3" (assuming that you've got Windows installed to C:\WINDOWS)
4) Delete the files in that directory (if they won't delete, make sure you've stopped monitoring, and that loop mode is off)
Part 2 - Collect data
5) Turn "Loop Mode" back on
6) Choose "Start Monitoring" from the RATT system tray icon menu
7) Run your computer for several minutes or longer (you can run Scratch LIVE during this time)
Part 3 - Grab the summary and upload it
8) Choose "Stop Monitoring" from the RATT system tray icon menu (this will create the summary file and then start monitoring again in the background)
9) Upload the file called "<your_computer_name>.cswa-accumulator-report.txt" from "C:\WINDOWS\system32\LogFiles\RATTV3" to scratchlive.net
10) Post a message in this thread in the following format:
Hardware: Toshiba Satellite 3.2GHz Pentium (HyperThreaded)
Operating System: Microsoft Windows XP Home Edition (Service Pack 2)
Ran Scratch LIVE During Test: No
Minimum Safe Scratch LIVE Buffer Size: 3ms
URL of Uploaded File: <url from uploading step 8 above>
Other Notes: ACPI turned off, WiFi turned on
Feel free to rerun the test and upload more results if you use different setups (networking on or networking off, ACPI on or ACPI off) that affects your safe USB buffer size.
Thank-you for your help!
