Google and a group of partners have released a set of tools designed to help broadband customers and researchers measure performance of Internet connections.

The set of tools, at MeasurementLab.net, includes a network diagnostic tool, a network path diagnostic tool and a tool to measure whether the user’s broadband provider is slowing BitTorrent peer-to-peer (P-to-P) traffic. Coming soon to the M-Lab applications is a tool to determine whether a broadband provider is giving some traffic a lower priority than other traffic, and a tool to determine whether a provider is degrading certain users or applications.

The tools will not only allow broadband customers to test their Internet connections, but also allow security and other researchers to work on ways to improve the Internet.

The M-Lab project, launched Wednesday, comes after controversy over network management practices by Comcast and other broadband providers. Earlier this month, two officials at the U.S. Federal Communications Commission questioned why Comcast, the largest cable modem provider in the U.S., was exempting its own VoIP (voice over Internet protocol) from traffic congestion slowdowns, but not offering the same protections to competing VoIP services.

The FCC letter to Comcast came after commissioners ruled in August that the broadband provider’s decision to slow some P-to-P traffic violated the agency’s network neutrality rules prohibiting broadband providers from blocking or slowing Internet traffic or applications. News reports in late 2007 unveiled Comcast’s practice of slowing some BitTorrent traffic. Comcast later said it was slowing traffic only at times of peak congestion, but the FCC and other groups disputed that the traffic management was limited.

Comcast declined to comment on the M-Labs effort.

The set of tools will allow broadband customers to measure their providers’ performance, said Michael Calabrese, director of the Wireless Future Program at the New America Foundation, a think tank involved in the M-Lab project. Consumers “deserve to be well-informed” about their broadband performance, he said.

Some of the M-Lab tools have already been released, but participants in the project plan to further develop the tools and host them on servers around the world, added Sascha Meinrath, research director at the Wireless Future Program. All the M-Lab tools will be released under open-source licenses, allowing others to modify and improve them, he said.

When Google launched offline GMail they promised it would act almost exactly like regular Gmail. From my early testing, it seems like that claim isn’t entirely true — in some ways, offline Gmail actually works better than the online version.

The main difference is speed. Regular Gmail is generally fairly quick, but you can still find yourself waiting at times for it to check in with Google’s servers. In offline mode or the very cool Flaky Connection Mode, everything — opening messages, searching for information, labeling missives — happens almost instantly, since all the data is local.

The tradeoff is that you don’t have access to all of your mail.

Google says, in essence, that it downloads your 10,000 most recent messages (they estimate that will cover several years for average users). But they also say that they identify your most important email threads and sync those. That’s a fascinating idea that’s not terribly well explained.

Here is what they say,

“We try to download your most recent conversations along with any conversations that seem to be important (regardless of their age). We also try not to dowload uninteresting conversations. This process is done heuristically and as with any heuristic can and will miss things. We’ll continue to tune things up, but more importantly, we’ll eventually provide a UI that will allow you to change the settings. Here’s a sketch of how these messages are selected:

Synchronization is based on the date of conversations. The system estimates a period of time to cover (at least 1 week in length) that results in approximately 10,000 messages being downloaded. For an average user, this means Gmail will end up downloading several years of mail.”