movies, stat latency

It's all Jon Johansen's fault. Without him, I wouldn't be able to watch the DVD's I borrow from the library. Now I get home and expect to be entertained every night. Just in the last week:

  • L'enfer: Watch a guy slowly go nuts. I think I prefer a plot that's not one long straight line.
  • Fierce Creatures: It has some pretty funny ideas, but just not nearly enough. In places where "Noises Off" would have a surprising event every second, "Fierce Creatures" would have a bunch of people running around looking frantic.
  • Earth Girls are Easy: OK, this was more fun, though honestly I'm not sure I'll remember it a week from now.

I should read more. In fact, our book group meets tomorrow to discuss "Flow My Tears", and I only read it once fairly quickly a couple weeks ago. I should give it another look before tomorrow night's meeting.

Sara and Paul went birdwatching Saturday morning. I couldn't see getting up before 7am just to look at some birds. But I guess it was quite the morning for it--when I met them for breakfast afterwards they were full of stories of baby swans, vultures, bird nests, and more.

The version control system we use for kernel work, "git", has a problem when running on an NFS filesystem--it detects when files change by calling stat() on them and looking for differences in modification time, size, inode number, etc. That means it can skip having to examine the data of unchanged files, but it still requires stat'ing every file in your working directory--and the linux kernel source has over 20,000 of them. The average ping time to my NFS server is about .2 milliseconds, so a round-trip to the server to request stat information will take at least that long. That means the whole tree will take at least 20000*.0004 = 4 seconds. In practice it ends up being over 10 seconds. A lot of git operations require this, so the delay gets really annoying. On a local filesystem, by contrast, the time is less than a quarter-second, once you've done it once (and the operating systems has cached all that stat data in memory).

NFS does some caching too, but to make sure that it notices file changes made by other clients it has to go back to the server every now and then. And you can tell it to do that less frequently, but then it becomes annoying when you use two clients at once and have to wait for changes made on one to be noticed on the other.

One possible fix is to make the server give out delegations more aggressively--a delegation allows the server to tell the client when a file changes, instead of making the client ask all the time. Thanks in part to a bright intern that's been learning his way around the server code, I think I'll have some help with that.

Another approach is to teach git to do those stat's in parallel, instead of sending all 20-thousand-some requests sequentially. That was my project for Sunday, but I didn't end up getting any further than finding the spot in the code that I'd need to modify to make it work. Maybe next weekend. This is sort of a hobby project, so I'm mostly ignoring it during the week.

home for a day

I was woke up earlier than usual with a stomach on fire, sent email saying I'd be home sick for the day, then tried to nap for the rest of the morning. A few hours later, I was fine. Maybe I ate something bad. So I did a little work from home in the afternoon, but had trouble concentrating.

Last night we watched the last half-hour or so of "Lage Raho Munna Bai", a movie that turned out to be much better than its ludicrous premise might suggest. Tonight we watched "Funny Face", which I expected to be good but wasn't. It had Fred Astaire and Audrey Hepburn in it, and that's about all you could say for it--they both did better elsewhere. I guess it did have its moments. The portrayal of hip intellectual life in Paris is bizarre.

I have a ton of work to get done tommorrow. Hopefully I'll be feeling in better mental shape.

rainy weekend

Sara noticed recently that the Peonies in the Arb were in bloom, so we'd planned a picnic in the peony garden. But the weather didn't cooperate. Instead we juggled on the Diag for a while, then made a dash indoors to the nearby chemistry building atrium, then had some food at pizza house, then finally (the rain having mostly subsided) walked around the peony garden for a while.

Pizza House is popular and ever-growing--word has it it's now the largest restaurant in ann arbor--but I'm not completely sure why. The food is usually OK, but nothing special. The prices are mostly reasonable, but it's not really cheap either. They seem to be in a state of permanent confusion--this time they told us there was nobody upstairs, when a later phone call revealed that some of our friends had already been seated there--then they got two out of seven orders wrong, and there were a few other minor hassles. I'm also annoyed that they consistently refuse to advertise their drink prices--if you want something, you either just order and hope, or ask someone (who usually has to go back to the kitchen to get the answer).

At least they didn't serve any glass in our food, which is what happened (with this same group of friends) a few years ago. I have no idea why we still go there.

Anyway, the peonies were nice. Afterwards we watched "noises off", which was more fun than I expected, though it's a bit frantic and I was a too tired to really keep up with every twist.

Sunday I had dinner at a former citi student's house with a couple other citi people.

Sara and I have also been watching "Lage raho munna bhai", a comedy about a gangster driven to become a follower of ghandi by love of a radio personality. It's actually a lot better than I expected.

Today I took care of my laundry and a few other chores in the morning. But it ended up stretching into the afternoon, and here I am at work late in the day, writing about my weekend. So I'm just writing off today as vacation. The current job offers more vacation than I use, so it's been piling up anyway.

doctors and students

Peter's student Jiaying defended Tuesday morning; total audience: four committee members and me. Her talk was actually pretty good, but they have this odd rule about the questioning occurring between only the committee and the student which meant I probably missed the interesting part. I should have protested.

I juggled a little on the diag after work.

The last couple nights, Sara and I watched the first two episodes of the "new" (except, there's a newer one now maybe?) Doctor Who. I never watched the original, really, but to me this seemed to have a lot of the same flavor--despite the new effects technology, it still feels like most of the aliens have socks on their heads, and the second episode depended on a countdown to build suspense. They weren't really funny enough to make it worthwhile to me.

Today I spent some more time with our interns, getting one started on a new project, and trying out their distcc setup. It was fun.

long weekend

I had all sorts of plans for my weekend, but none really materialized. Instead I read some Wodehouse--"Jeeves and the Tie that Binds"--and some Pinkwater--"The Education of Robert Nifkin", and "Alan Mendelsohn, Boy from Mars". OK, the latter I didn't need to reread. I liked "Robert Nifkin", though. It reminds me of what I miss living in Ann Arbor. I miss the sense that I have wandering around some big cities, that there could always be something strange and wonderful around the next corner.

I made a library trip yesterday and got a couple Fred Astaire movies. Last night we watched "The Gay Divorcée". It has basically the same actors playing the same parts as in "Top Hat", but maybe not as much dancing. Oh well. We got a kick out of it anyway.

Toronto to Ann Arbor

Friday morning I hung out at the B&B and did some work while Sara went to a few final sessions, then we met Janet at the train station for our noon train to Windsor. The train ride went fine. And they had power and network--what else could a travelling geek need? The wireless service actually wasn't too bad, if maybe a little pricey.

Janet's husband met us at the Windsor station and dropped us off at home.

music garden, linux café

In a further departure from my usual refusal to plan anything while on vacation, I did a little looking around with Google and my guidebook in the morning after the usual breakfast routine.

I was delighted to find out about the "music garden". It's just a few blocks south of the B&B, was designed in part by Yo-Yo Ma, and consists of six little subareas, one for each part of the first Bach Cello suites. So I loaded the suite off my laptop onto my music player and headed there first. I spent enough time there to walk through the six gardens twice, and listen to each piece three times or so. They've found a way to trick me into looking at gardens! Usually my patience for them is more limited.

I'd also noticed the existence of a "Linux Café" well North of there, so I'd decided to go camp out there for lunch. It was a funky little coffeeshop, with a counter in front and tables full of people at laptops off to the side. Most of them seemed to actually be running Windows or OS X, but there was a guy showing off a prototype from the "One Laptop per Child" program to another patron. Neat-o. I listened in for a while and ask some questions. I ended up getting to play with it for half an hour or so.

The OLPC machine is small, light, and totally adorable. Unfortunately, it's also nearly unusable for someone with adult-sized hands--the keyboard is definitely meant for kids. The user interface is OK when running a single program, but very sluggish when switching tasks. That and the fact that it's a completely novel interface makes it a little confusing to work with. But it's a really impressive bit of technology.

I walked back to the convention center to meet Sara for dinner. We had a hard time figuring out where to eat, but eventually ended up some place a couple blocks from there that was a little overprice, but good, and fast--important because Sara had another meeting to go to after dinner.


Another breakfast like yesterday's, with Sara off for her conference at nine.

Determined to solve my Phillip K. Dick problem, I tried a google search that found me a science fiction bookstore well West of us on Queen street. They didn't open till 11, so I hung out at the B&B for a while, then took a roundabout route there. I enjoyed looking at the nearby neighborhoods. A lot of them are these old duplexes, with a fine line up the center (often splitting a little peaked roof down the center) dividing the two halves. Often the two halves had been painted two different colors. I found the effect kind of comical.

The bookstore was small and their selection had some odd gaps, but they rashly shelved their Phillip K. Dick right there where anybody could get to it. The price for my book was a little steep--the Canadian prices seem more appropriate for exchange rates of a few years ago--but I took a copy anyway.

My next "plan" for the day was to walk to a French-language bookstore across town and get lunch along the way. I don't think I'd realized quite how far it was. But I stopped in several parks along the way, read several chapters of "Flow my Tears", and enjoyed the sight of a statue of a grumpy Winston Churchill with a seagull perfectly perched on top and droppings running down his forehead.

There first part of the walk was stuffed full of restaurants, and I was kind of picky, assuming there'd be many more choices, but then they thinned out dramatically. The downtown part of Queen is a little sterile, and east of there it seems a little economically depressed. But then a few blocks from my destination I saw a little place called the "Berkeley Café" on a side street. It had a few contented-looking customers but wasn't too busy, so ordered a sandwich and settled in with my book. The sandwich was yummy and came with a nice salad, and I had an even more yummy pecan tart for desert. Nobody seemed to be in a rush, so I stretched the whole thing out over at least an hour and got a lot of "Flow my Tears" read.

The French bookstore was large but had kind of an odd selection. Among other things it shared the dismal publisher-based arrangement of fiction that I saw in bookstores in Paris. Does anyone actually walk into a bookstore saying "I think I'd like a little something from Gallimard today?" Am I supposed to know who published Queneau's "Dimanche de la Vie"?

The only things I found that I was really interested in were a few comics which were on the expensive side, so I chose just two of them and started the leisurely walk back. This time my main reading stop was a little park in front of a church that had a nice carillon concert going on and a bunch of marginal-looking characters intent on their chess games.

I went into a big mall downtown on Yonghe for a bathroom break and a drink, then admired a little plaza with a nice labyrinth in the pattern on the stone--a simple, circular, and (to the extent possible) relatively symmetric pattern that nevertheless managed to be just a single line with one entrance and exit. I copied down the pattern in a notebook. Then I went and sat at a bigger public square across the street, read some more, and did some work on my laptop.

I got some crêpes on Queen street for dinner. On my way back to the B&B I lingered outside a jazz club with some lovely-sounding big-band music and thought darn, I should have gone there. But my crêpes were pretty good, so I couldn't really complain.

Sara was already at the B&B when I got back.


Left to my own devices, I don't tend to read guidebooks or look for sights. That seems more like work than vacation to me. But that's probably kind of a dumb attitude, and I feel sort of self-conscious about it, so I usually try to give myself some minor goals for the day anyway.

The guidebook Sara checked out of the library had two public libraries listed in downtown Toronto, so I set those as my sort-of-goals for the day.

So, after breakfast--assorted fruit, yogurt, then a plate of hot food with a couple fried eggs, bacon, toast, and tomato wedges--I made my slow way up Spadina to a library branch across from the University of Toronto campus on College street. It wasn't open yet, so I wandered on a little further, found an intersection a few blocks down with a nutty-looking traffic pattern, and sat and watched for over half an hour.

Toronto has many more cyclists than Ann Arbor--at this particular intersection there were often 8-10 cyclists lined up from one direction when the light turned green. The street had two lanes of car (and streetcar) traffic each way, and a bike lane on each side. The bike lane stayed on the right throughout. There was also a lot of right-turning car traffic. If I were riding straight through that intersection, I'd merge left into the rightmost car lane before going through the intersection, and if I were driving and turning right, I'd merge over to the right to block the bike lane first. But with a couple exceptions everyone was waiting till the last minute to cross each other's path.

But interestingly, the only bike/car conflicts I saw were between straight-through cyclists and left-turning drivers facing them. I think what happened was that straight-through car drivers hung back as the lane ahead of them filled up (traffic was that backed up), and then the left-turners facing them assumed no-one was coming and cut across the path of a cyclist emerging from behind the rightmost car lane on the other side of the street. Either that, or some cyclists were just running red lights.

The library had a special science fiction collection upstairs, and I spent a few minutes looking at some of the stuff they had out on display. It would've been more interesting if I'd had some old edition in mind from the closed stacks that I wanted a look at, but I didn't.

So I found a nice spot at a table downstairs, forked over for a city-wide wireless network, wrote a couple patches, sent them in, and handled some email before moving on. It was fun.

I roamed around and looked at odd buildings on the campus for a while (it has lots), got a sandwich at a Tim Horton's, then visited the reference library on Yonghe, which has a really impressive building. It looked like a nice place to hang out and work, too, though their network seemed a little dodgy.

Then it was back down Yonghe to meet Sara at the convention center.

Another side project for my day had been to find an electronic shaver to replace one I broke recently. I found something at a Sears. I was less succesful at finding a copy of Dick's "Flow my Tears, the Policeman Said", our next book group book. One bookstore had just a few Dick books, two used bookstores had none at all on the shelves--one of them had a single book behind the counter, but the wrong one. Is there an anti-Dick conspiracy?

On our way to find dinner, Sara and I got an explanation from the guys behind the information counter at a big chain bookstore, where we were surprised to discover a little marker on the shelf saying "ask at the information desk for books by this author." We asked. They explained that Dick (along with, for some reason, Murukami), was one of the most shoplifted authors. Apparently they have high resale value. Anyway, "Flow My Tears" wasn't among the few books they had behind the counter.

We ended up at a place called "Hungary Thai", thanks to the interesting (Hungarian-Thai) menu and the pun. It was pretty bad--may we should have noticed that there weren't any customers. Sara's beef paprakish was good but ordinary, and my Thai curry was unusually tasteless and came with underdone rice.

Ann Arbor to Toronto

I'm writing these from notes a week later. I don't normally backdate my entries. Oh well.

"Today" Carl picked us up from home at 9am, then picked up Janet, then we were off. We stopped noonish sometime after crossing the Port Huron/Sarnia border, at a place advertising Chinese and Canadian food. I got a BLT, Sara got some Chinese dish I forget, and the others got club sandwiches. No complaints. It's a holiday (Victoria day?) and lots of businesses were closed.

When we arrived in Toronto they first dropped off Sara and I at our bed and breakfast, which was in a frumpy row of cute old row houses lining either side of two-thirds of one block in a neighborhood that seemed otherwise pretty industrial. They then left to find their hotels.

After we were settled in we took the ten-minute walk downtown to the convention center. The expected attendance at the ASM meeting was over 10,000, and the crowd was impressive. Sara registered, then we parted ways. We tried to figure out whether I should meet her at the end of her opening reception, but it turned out to be at a science museum across town someplace that they were all being shuttled to.

I roamed for a while poking in bookstores and looking at restaurant menus, finally settling on a Korean place somewhere east of the convention center, which had the usual complement of excellent veggie side dishes. Satisfied, I walked back to the bed and breakfast and read "Riddley Walker" until Sara got back.


Subscribe to RSS