Move along, nothing to read

On Tuesday for OLS2008, I attended the wireless mini-summit. In past years, fellow Gentoo developer dsd has attended, and was remember by some of the attendees. I'm not so much involved with wireless stuff these days, but I have a good grasp of it from back when I worked at Net-Conex doing point-to-point links using Airaya WirelessGRID 802.11a gear doing 108Mbit w/ AES256, plus personal experimentation.

The vendors (Intel, Marvel, Broadcom, Atheros, Ralink, Nokia and others) and major distributions (Fedora/RH, Ubuntu, Debian, Suse) were present, but I was the only attendee from the smaller distros. Also present were some of the other core wireless developers, incl. Johannes Berg.

Most of the talk focused on 802.11 stack and driver issues, with a presentation about WiMax from Intel.

One of the really interesting things was the work from Luis R. Rodriguez, on the new Central Regulatory Domain Agent (CRDA). There were some large questions from the Intel crowd about API and interaction, but the general concept was very well received. The support for signing the domain file is probably going to not be used for the most part, as there are too many other places to subvert usage of the data even if the file is signed. 802.11d and 802.11h are mostly considered as useless as apparently no regulatory agencies have signed off on them.

Another interesting discussion came out of the discussion on power management. Stuff on the usage of the CARRIER interface flag. It's apparently quite inconsistent, and the UP/DOWN status on some wireless devices has large implications. Some devices go totally away on DOWN, and need firmware loaded on UP. In some, the power consumption in reset state prior to loading firmware is lower than any other powered-down state. Multiple power levels may be added later to try and allow devices to define what states are best/available for their power saving. Implications of firmware loss and DOWN state on associations to APs, esp. when some parts of WPA are in play. This all also sucks with some DHCP clients as they perform DOWN on release or failure, which loses the firmware - such behavior from userspace really needs to be stamped out.

For lunch, we went to a buffet resturant, Tuckers. I was a little dubious of this at first, as buffet is really not my thing, however I can say that it was quite decent, esp. their roast beef carvery, with some nice whole-grained mustard. The salads weren't so great, but overall I think I'd eat there again in a group if there was sufficient group demand.

On the way out of lunch, I ran into a cute girl (I'll call her A) with a rubber-spiked laptop bag, and started chatting to her. As she was an Ottawa resident, she was prepared with an umbrella for the torrential summer rain that started during lunch. Sharing her umbrella we returned to the hotel conference rooms, splitting up thereafter as she was in the virtualization mini-summit.

Post-lunch, resuming the wireless mini-summit, we discussed more issues about the CRDA, core mac80211 development, and then breakout sessions on power-management and ??? (I can't remember what the other side was, even though I was in it).

For dinner, I took a clear walk out via parliament, and a very long way, full route. Ended up at "Elgin Street Freehouse" for dinner, had an Indian-fusion twist on steak, and did manage to find virgin Mojitos successfully. Nice 5km walk for exploring.

As one talk I was really interested in, I went to John Hawley's talk entitled "Issues in Linux Mirroring: Or, BitTorrent Considered Harmful", as seen from the perspective of the kernel.org mirrors.

This paper was really interesting for me, both as the Gentoo releng infra liasion (I get the bits from releng onto the mirrors), as well as working for IsoHunt, since he was complaining about BitTorrent.

Before the actual material about BitTorrent, he had some harsh words about distributions and space usage, and the lack of co-ordination. Having multiple major distributions doing their releases in the same week really only hurt themselves, because the mirrors get saturated by users. Between two major distros, they use up fully half of the 5.5TiB at kernel.org, and having them doing new material at the same time just blows out the cache, even with stupid amounts of memory. (Comments were made about Mark Shuttleworth having the money to buy some boxes with TiB of RAM for kernel.org). Co-ordination between distributions is needed to resolve this issue, and the audience discussion suggested we should try the distributions@freedesktop list first, and if that's too much noise, start up a list at kernel.org instead.

Moving onto BitTorrent, he noted that in large Linux torrent swarms, the standard tracker balancing algorithms end up with a net effect that a few slow peers joining greatly slow down the swarm speed at present (based on analysis of the tracker used by Fedora for the F8 release). If mirror are performing seeding, in many cases, it will still be faster for the mirror to provide content for a given user than other client peers. If the objective is to move content as fast as possible, this is needed vs. the normal BT objective of balancing total bandwidth usage.

Issues for distributions in handling bittorrent to make life easy for mirrors, he had several complaints about the level of manual interaction needed, to which I responded with the Gentoo structure of symlink trees under experimental, which is used for mirrors to run torrents easily, as well as powering the HTTP seeding additions to the BitTorrent protocol.

In using rtorrent(libtorrent), he complained that it wasn't using sendfile at all, which had a large negative performance impact, should be tackled upstream.

The BitTorrent community also needs to look at tweaking the peer decision protocol in the announce protocols, to hand out a smarter selection of fast peers. Where fast is local (look at BGP looking-glass for clues) or is a designated fast mirror that should be used as a fast peer.

Lastly, he noted that the trackers seem to be badly run, as somebody from isoHunt, I offered to post up my own work on running effective trackers to the inter-distro discussion.

So I previously wrote about the fun with clearing security. My flights were reasonably uneventful. Had an overpriced, soggy prime rib sandwich on the first flight, watched "Flawless" with Demi Moore and Micheal Caine - pretty good movie, on the overhead screen. Air Canada fun in that they have the frames for the in-seat TVs, but there aren't TVs, just little cushions.

Got in to Toronto on time, dashed over the length of terminal one to get to my other flight, it's nicer now with a lot of construction finished. Stopped at the Chocolate store and bought some honeycomb toffee (the stuff inside Crunchie bars).

Next hop was Ottawa, in a small Embrauer jet. In-seat touchscreen displays, with a USB A socket, but no accessible system (it did video for the safety, then had a windows cursor on a logo).

My luggage beat me off the plane, and I picked up a folding plastic map of Ottawa. Grabbed bus tickets at the info desk, and caught the bus to downtown. Nice on dedicated busways, 25 minutes to downtown, then a short walk to the hotel.

Checked in, massive suite - nearly the size of my basement. Living room, bedroom (w/ queen size bed), bathroom, laundry (washer+dryer), kitchen (fridge, stove, microwave, dishwasher) - all old appliances, late 80s look, but functional. Not much in the cupboards, just the bare minimals.

Finished my book from the plane, showered, wrote an email to John Linville to see about the wireless mini-summit. Walked out to the elevator, and ran into John. He was recruiting a group for dinner, which I joined after doing my conference registration. Walked out toward Byward Market, trying to find a place for 14 people for dinner, ended up in the back of a Vietnamese place.

Ate a very tasty lamb, mushroom, onion stir-fry, with two Stellas to drink. Afterwards, the east coast people as well as those from Europe were all heading for bed, but west-coast folk were getting together for drinking - since it was still quite early by our clocks. Went with them, the four of us ended up at an Irish place, that didn't have mint for Mojitos or any other drinks, so we were to drink beer instead. Talking lots accidently lead to too many beers. I previously reported 7 beers, that was drunken miscounting, because we only ordered 4 pitchers, and each of the pitchers held 3.5 beers. Divided by four people, that's only 3.5 beers - added to the other two from dinner, leads to a total of 5.5.

However that was clearly too much, as it didn't sit well later, and made returns before I went to bed.