Stuff I have written/presented
Submitted by gwolf on Thu, 08/21/2014 - 00:34
I still consider myself a newbie teacher. I'm just starting my fourth semester. And yes, I really enjoy it.
Now, how did I come to teaching? Well, my training has been mostly on stages for different conferences. More technical, more social, whatever — I have been giving ~10 talks a year for ~15 years, and I must have learnt something from that.
Some good things, some bad habits.
When giving presentations, a most usual technique is to prepare a set of slides to follow/support the ideas. And yes, that's what I did for my classes: Since my first semester, I prepared a nice set of slides, thematically split in 17 files, with ~30 to ~110 pages each (yes, huge variation). Given the course spans 32 classes (72 hours, 2¼ hours per class), each slide lasts for about two classes.
But, yes, this tends to make the class much less dynamic, much more scripted, rigid, and... Boring. From my feedback, I understand the students don't think I am a bad teacher, but still, I want to improve!
So, today I was to give the introduction to memory management. Easy topic, with few diagrams and numbers, mostly talking about the intuitive parts of a set of functions. I started scribbling and shortening the main points on a piece of paper (yes, the one on the picture). I am sure I can get down to more reduction — But this does feel like an improvement!
The class was quite successful. I didn't present the 100% of the material (which is one of the reasons I cling to my presentations — I don't want to skip important material), and at some point I do feel I was a bit going in circles. However, Operating Systems is a very intuitive subject, and getting the students to sketch by themselves the answers that describe the working of real operating systems was a very pleasant experience!
Of course, when I use my slides I do try to make it as interactive and collaborative as possible. But it is often unfeasible when I'm following a script. Today I was able to go around with the group's questions, find my way back to the outline I prepared.
I don't think I'll completely abandon my slides, specially for some subjects which include many diagrams or pictures. But I'll try to have this alternative closer to my mind.
Submitted by gwolf on Tue, 08/19/2014 - 23:10
Summer is cool in Mexico City.
It is cool because, unlike Spring, this is our rainy season — And rains are very predictable. Almost every day we wake up with a gorgeous, clean, blue sky.
Cool, nice temperature, around 15°C. The sun slowly evaporates the rain throughout the morning; when I go out for lunch, the sky is no longer so blue, giving way to a seemingly dirty white/grayish tint. No, it's not our world-famous pollution: It's just yesterday's rain.
Rain starts falling usually between 4 and 7 PM. Sometimes it starts as a light rain, sometimes it starts with all of its thunder, all of its might. But anyway, almost every night, there is a moment of awe, of not believing how much rain we are getting today.
It slowly fades away during the late night. And when I wake up, early next morning, everything is wet and still smells fresh.
Yes, I love our summer, even though it makes shy away from my much enjoyed cycling to work and school. And I love taking some minutes off work, look through the window of my office (located ~70m over the level of our mostly flat city) and watching how different parts of the city have sun or rain; learning to estimate the distance to the clouds, adding it to the direction and guessing which of my friends have which weather.
But I didn't realize our city had so clearly defined micro-climates... (would they really be *micro*-climates?) In fact, it even goes against my knowledge of Mexico City's logic — I always thought Coyoacán, towards the South of the city, got more rain than the Center and North because we are near the mountains, and the dominant air currents go Southwards, "clumping" the clouds by us.
But no, or at least, not this year. Regina (still in the far South — Far because she's too far away from me and I'm too egocentric; she returns home after DebConf) often asks me about the weather, as our friends working nearer the center of the city. According to the photos they post on their $social_media_of_the_day accounts, rains are really heavier there.
Today I heard on the radio accounts of yesterday's chaos after the rain. This evening, at ESIME-Culhuacán, I saw one of the reported fallen trees (of course, I am not sure if it's from yesterday's rain). And the media pushes galleries of images of a city covered in hail... While in Copilco we only had a regular rain, I'd even say a mild one.
This city is bigger than any cloud you can throw at it.
Submitted by gwolf on Fri, 08/01/2014 - 11:32
Yes, I've been bragging about the Operating Systems book all over... Today, a colleague handed me a phone call from somebody at Editorial Patria, a well known educational editorial in Mexico. They are looking for material similar to what I wrote, but need the material to be enfocado a competencias — Focused on skills, a pedagogic fashion.
I was more than interested, of course. As it currently stands, I am very happy that our book is being used already at three universities in three countries (by the different authors) and have heard other people saying they would recommend it, and of course I'm interested in making our work have as big an impact as possible. Of course, we'd have to modify several aspects of the book to cater to the skills focus... But it would be great to have the book available at commercial bookstores. After all, university editions are never as widely circulated as commercial ones.
I had just one hard request to accept this: Our work must be distributed under a free licensing. Explicitly allow book photocopies and electronic distribution (didn't get into the "and modification" part, but I would eventually get there ;-) )
And... Of course, the negotiation immediately fell down. Editorials, this person says, live from selling individual books. She says she was turned down by another university professor and for another subject this same week.
So, yes, I took the opportunity to explain things as I (and the people that think as I do — Fortunately, not so few) see them. Yes, of course, editorials have to make a living. But text books are often photocopied as it is. Who buys a book? Whoever needs it. On one hand, if somebody will be using a book throughout a semester and it's reasonably priced (say, up to 3×cost of photocopies), they will probably buy it because it just works better (it is more comfortable to use and nicer to read).
If a teacher likes the explanation for a particular topic, it should be completely legal for him to distribute photocopies (or digital copies) of the specific material — And quite probably, among the students, more than one will end up appreciating the material enough to go look for the book in the library. And, as I have done throughout my life, if I read (in copies, electronically or in a library) a book I like... Quite probably I will go buy it.
So... Of course, she insisted it was against their corporate policy. I insisted on my explanation. I hope they meet many stubborn teachers refusing to distribute books under a non-free licensing. I hope I contributed to making a dent in an industry that must change. Yes, a very very small dent, but one that helps them break free from their obsolete mindset ;-)
(But yes, I don't know how long I will regret not being part of their very nice catalog of science and engineering books) ;-) )
Submitted by gwolf on Tue, 07/29/2014 - 13:09
Today I finally submitted our book, Fundamentos de Sistemas Operativos, for the Editorial Department of our institute. Of course, I'm not naïve enough to assume there won't be a heavy editorial phase, but I'm more than eager to dive into it... And have the book printed in maybe two months time!
Of course, this book is to be published under a free license (CC-BY-SA). And I'm talking with the coauthors, we are about to push the Git repository to a public location, as we believe the source for the text and figures can also be of interest to others.
The book itself (as I've already boasted about here :-} ) is available (somewhat as a preprint) for download.
[update] Talked it over with the coauthors, and we finally have a public repository! Clone it from:
Submitted by gwolf on Thu, 07/24/2014 - 22:18
A long time ago, I did some (quite minor!) work on natural language parsing. Most of what I got was the very basic rudiments on what needs to be done to begin with. But I like reading some texts on the subject every now and then.
I am also a member of the ACM — Association for Computing Machinery. Most of you will be familiar with it, it's one of the main scholarly associations for the field of computing. One of the basic perks of being an ACM member is the subscription to a very nice magazine, Communications of the ACM. And, of course, although I enjoy the physical magazine, I like reading some columns and articles as they appear along the month using the RSS feeds. They also often contain pointers to interesting reads on other media — As happened today. I found quite a nice article, I think, worth sharing with whoever thinks I have interesting things to say.
They published a very short blurb titled The Fasinatng … Frustrating … Fascinating History of Autocorrect. I was somewhat skeptical reading it links to an identically named article, published in Wired. But gave it a shot, anyway...
The article follows a style that's often abused and not very amusing, but I think was quite well done: The commented interview. Rather than just drily following through an interview, the writer tells us a story about that interview. And this is the story of Gideon Lewis-Kraus interviewing Dean Hachamovitch, the creator of the much hated (but very much needed) autocorrect feature that appeared originally in Microsoft Word.
The story of Hachamovitch's work (and its derivations, to the much maligned phone input predictors) over the last twenty-something years is very light to read, very easy to enjoy. I hope you find it as interesting as I did.
Submitted by gwolf on Fri, 06/27/2014 - 20:46
I stared at Noodles' Emptiness, where I found a short rant on the currently most used forms of communication. No, into the most socially-useful forms of communication. No, into what works best for him. And, as each person's experience is unique, I won't try to correct him — Noodles knows himself much, much, much, much better than I do. But some people have wondered recently (i.e. at conferences I have been at) why I give such an atypical use to social networks (...a term which I still hold to be grossly misused, but that's a topic for a different rant...One that's been had too many times).
So, although my blog is syndicated at Planet Debian, and I know a good deal of readers come from there, this post is targetted at the rest of the world population: Those that don't understand why many among us prefer other ways of communication.
Noodles mentions seven forms of communication he uses, arguably sorted by their nowadayness, low to high: Phone call, text (SMS) message, email, IRC, Skype, Google Hangouts and Facebook messenger.
Among those, I strongly dislike two: Phone call and Skype (or any voice-based service, FWIW). I do most of my communication while multitasking, usually at work. I enjoy the quasi-real-timeliness of IRC and the instant messengers, but much more, I like the ability to delay an answer for seconds or minutes without it breaking the rules of engagement.
Second, if the ordering is based on what I found, the reason for my little rant should become obvious: We had kept a great job so far building interoperable technology.1 Up until now, you could say «drop me a mail», and no matter if you had your mail with GMail and I insisted on self-hosting my gwolf.org, as long as our communications adhered to simple and basic standards, we would be perfectly able to communicate.
Skype is a bit of a special case here: They did build a great solution, ~ten years ago, when decent-quality VoIP was nowhere to be found. They have kept their algorithm and mechanisms propietary, and deliberately don't operate with others. And, all in all, there is a case for them remaining closed.
But Google Hangouts and Facebook Messenger do piss me off. More the first than the second. Both arrived to the instant messenger scene long after the experimentation and early stages, so they both took Jabber / XMPP, a well tried and tested protocol made with interoperability and federability in mind. And... They closed it, so they can control their whole walled garden.
PS- Interestingly, he left out the face-to-face communication.I am quite an anchorite in my daily life, but I still think it's worth at least a mention ;-)
So, Noodles: Thanks for the excuse to let me vent a rant ;-)
Submitted by gwolf on Sun, 06/22/2014 - 01:06
Only a very short summary in English: I am Mexican. I am Jewish. I am almost completely disconnected from the local Jewish communities. And understanding the local Jewish communities is hard. There is a very interesting and brave campaign, recently started, called Neither do I — The Mexican Jewish gay activist group Guimel, started off with this video (with English subtitles, if you are interested in following along). But how did I learn about this very bold initiative? By getting a hateful spam, inviting people to join a hate campaign. Right, the hate mail is not calling to violence, but it is based on premises as stupid as everybody's right not to include (to begin with).
So, the least I can do about this is to share both said hate mail and publicly denounce my shock on reading this nonsense nowadays. And, also in Spanish (I know many people following me don't understand it — Sorry, it would just take too long, and after all, it's mainly for local "consumption"), this is the reply I sent to them (and to the other recipients). Sorry in advance to the Spanish speakers for my exabrupts :) This was written "as is", without much prior thought, and quite angry about what I had just read.
Submitted by gwolf on Mon, 06/16/2014 - 19:54
So, after writing my last blog post in frustration, several people knowing their way around Tor better than me wrote that I should just configure my machine not to be an exit relay, but a middle relay or a bridge.
So, I set it up to be a bridge about five days ago. And, as they pointed out, I have not experienced any problems.
Interesting: The traffic pattern is very different. Compare:
Traffic pattern as an exit relay:
Traffic pattern as a bridge:
Anyway — I'm happy to have Lobazal back online!
Submitted by gwolf on Tue, 06/10/2014 - 12:07
Some days ago, I bit the bullet and accepted the Tor Challenge.
Sadly, after only four days of having a Tor relay node happily sitting at home (and, of course, giving a nice function to this little friend). The inconveniences were too many.
I understand anonimity can be used for many nefarious things, but I was surprised and saddened to see the amount of blocking services. Most notorious to me were the Freenode IRC network, friendly home to many free software projects, and the different Wikimedia projects, which ban editting from IP addresses idenitfied as Tor relays.
I'm saddened to say that, while I could perfectly survive (and even be a bit proud about supporting a project I believe in) by jumping through some hoops (i.e. by setting up a SOCKS over ssh tunnel to my office to do my Wikipedia edits while at home), after only four days, I decided to shut down my relay.
And the main reason... Was something I'm not going to fight against. And it's not even from a nice, friendly free software project.
One thing I am not willing to part with is the one tool that keeps my wife well in contact with her friends and family back in Argentina. Yes, I know I could set up one or many different flavors of SIP or Jabber-based VoIP for her — But it's also her parents, brother, sisters, and friends who use Skype. So, Skype's banning of Tor relay nodes made me decide to shut down my relay.
Sigh... And for somebody obsessed with graphing stuff, this is the graph of the short lifespan of the "Lobazal" Tor node:
[update] I will do another blog post. Good news: My Tor node is alive again! Just no longer as an exit relay, as properly pointed out by many, but as a Tor bridge.
Submitted by gwolf on Thu, 06/05/2014 - 23:20
John states some very important reasons for people everywhere to verify the identities of those parties they sign GPG keys with in a meaningful way, and that means, not just trusting government-issued IDs. As he says, It's not the Web of Amateur ID Checking. And I'll take the opportunity to expand, based on what some of us saw in Debian, on what this means.
I know most people (even most people involved in Free Software development — not everybody needs to join a globally-distributed, thousand-people-strong project such as Debian) are not that much into GPG, trust keyrings, or understand the value of a strong set of cross-signatures. I know many people have never been part of a key-signing party.
I have been to several. And it was a very interesting experience. Fun, at the beginning at least, but quite tiring at the end. I was part of what could very well constitute the largest KSP ever in DebConf5 (Finland, 2005). Quite awe-inspiring — We were over 200 people, all lined up with a printed list on one hand, our passport (or ID card for EU citizens) in the other. Actwally, we stood face to face, in a ribbon-like ring. And, after the basic explanation was given, it was time to check ID documents. And so it began.
The rationale of this ring is that every person who signed up for the KSP would verify each of the others' identities. Were anything fishy to happen, somebody would surely raise a voice of alert. Of course, the interaction between every two people had to be quick — More like a game than like a real check. "Hi, I'm #142 on the list. I checked, my ID is OK and my fingerprint is OK." "OK, I'm #35, I also printed the document and checked both my ID and my fingerprint are OK." The passport changes hands, the person in front of me takes the unique opportunity to look at a Mexican passport while I look at a Somewhere-y one. And all is fine and dandy. The first interactions do include some chatter while we grab up speed, so maybe a minute is spent — Later on, we all get a bit tired, and things speed up a bit. But anyway, we were close to 200 people — That means we surely spent over 120 minutes (2 full hours) checking ID documents. Of course, not all of the time under ideal lighting conditions.
After two hours, nobody was checking anything anymore. But yes, as a group where we trust each other more than most social groups I have ever met, we did trust on others raising the alarm were anything fishy to happen. And we all finished happy and got home with a bucketload of signatures on. Yay!
One year later, DebConf happened in Mexico. My friend Martin Krafft tested the system, perhaps cheerful and playful in his intent — but the flaw in key signing parties such as the one I described he unveiled was huge: People join the KSP just because it's a social ritual, without putting any thought or judgement in it. And, by doing so, we ended up dilluting instead of strengthening our web of trust.
Martin identified himself using an official-looking ID. According to his recount of the facts, he did start presenting a German ID and later switched to this other document. We could say it was a real ID from a fake country, or that it was a fake ID. It is up to each person to judge. But anyway, Martin brought his Transnational Republic ID document, and many tens of people agreed to sign his key based on it — Or rather, based on it plus his outgoing, friendly personality. I did, at least, know perfectly well who he was, after knowing him for three years already. Many among us also did. Until he reached a very dilligent person, Manoj, that got disgusted by this experiment and loudly denounced it. Right, Manoj is known to have strong views, and using fake IDs is (or, at least, was) outside his definition of fair play. Some time after DebConf, a huge thread erupted questioning Martin's actions, as well as questioning what do we trust when we sign an identity document (a GPG key).
So... We continued having traditional key signing parties for a couple of years, although more carefully and with more buzz regarding these issues. Until we finally decided to switch the protocol to a better one: One that ensures we do get some more talk and inter-personal recognition. We don't need everybody to cross-sign with everyone else — A better trust comes from people chatting with each other and being able to actually pin-point who a person is, what do they do. And yes, at KSPs most people still require ID documents in order to cross-sign.
Now... What do I think about this? First of all, if we have not ever talked for at least enough time for me to recognize you, don't be surprised: I won't sign your key or request you to sign mine (and note, I have quite a bad memory when it comes to faces and names). If it's the first conference (or social ocassion) we come together, I will most likely not look for key exchanges either.
My personal way of verifying identities is by knowing the other person. So, no, I won't trust a government-issued ID. I know I will be signing some people based on something other than their name, but hey — I know many people already who live pseudonymously, and if they choose for whatever reason to forgo their original name, their original name should not mean anything to me either. I know them by their pseudonym, and based on that pseudonym I will sign their identities.
But... *sigh*, this post turned out quite long, and I'm not yet getting anywhere ;-)
But what this means in the end is: We must stop and think what do we mean when we exchange signatures. We are not validating a person's worth. We are not validating that a government believes who they claim to be. We are validating we trust them to be identified with the (name,mail,affiliation) they are presenting us. And yes, our signature is much more than just a social rite — It is a binding document. I don't know if a GPG signature is legally binding anywhere (I'm tempted to believe it is, as most jurisdictions do accept digital signatures, and the procedure is mathematically sound and criptographically strong), but it does have a high value for our project, and for many other projects in the Free Software world.
So, wrapping up, I will also invite (just like John did) you to read the E-mail self-defense guide, published by the FSF in honor of today's Reset The Net effort.
Submitted by gwolf on Tue, 05/27/2014 - 10:04
The picture explains it much better than what I ever could.
Submitted by gwolf on Sat, 05/17/2014 - 16:49
Yesterday night, we had the opportunity to have –for the first time– my friend Kaz as a guest in my Operating Systems class. We are about to finish the semester, and he took the opportunity not just to show how the Ext4 filesystem is structured, but how it is implemented in a current Linux release.
Kaz took a very different approach from what I do: He did it really hands-on, starting with the explanation on how a hello world module would be created, and then digging in following the code of the ext4 module in Linux 3.14 (and some bits in the general filesystem-related includes).
Of course, for a ~2hr session, he did not go into the full details, but did show where the main structures of a filesystem are defined, including a general walkthrough on the general kernel coding style.
The class was very enjoyable and clear. We had the bad luck of the projector's lamp burning out at the beginning of the class, but still, you can see in the pictures the students were really into his exposition. I think the exposition did make it through and got the students involved and interested — And that makes it really worth it!
Now... Sadly, due to a (most probably) human factor, I tried to record this talk but lost most of it :-( I have only the first part, but lost most of the second one. I have some bits recorded by a second camera, but have to check if they make sense by themselves, or do need the whole context. Anyway, I'll be reviewing those bits, and will update this post when I get around to cleaning+fixing+integrating them.
Submitted by gwolf on Sat, 05/17/2014 - 15:05
Shame on me... I should have uploaded this video a long time ago. I wanted to edit this video to remove pauses, add some in-band indications on who and what it is, and stuff... But after a month, I have not yet got around to do it.
On April 23, I invited César Yáñez to present a talk on virtual memory management to my students (for the Operating Systems class). As always (this is the third time I invite him — The previous iteration was on process scheduling, and is on my site as well), he gave a great class.
I still have some pending videos to upload from the other guests we had this semester, they should come shortly.
Submitted by gwolf on Mon, 05/05/2014 - 12:37
I was invited to give a talk at a local conference, OS-UPIITA. I have been invited to this conference before, and will gladly be there again. But I was recently pointed at the invitation poster they are distributing (which I reproduce here for your convenience) — And I must make a couple of corrections here:
But anyway, I will be very happy to be there, and believe me, am working to come up with a good talk.
OS-UPIITA friends: Please correct your online banners carrying this wrong data.
[update] OS-UPIITA changed the poster! I'm just keeping this one for the memory ;-)
[update 2] I was there, and gave the talk. And it was even a success, yay! \o/ Care to see it? Here is the presented material.
Submitted by gwolf on Tue, 04/29/2014 - 13:15
I have heard many good things about Docker, and decided to give it a spin on my systems. I think application-level virtualization has a lot to offer to my workflow...
But the process to understand and later adopt it has left me somewhat heart-torn.
Docker is clearly great technology, but its documentation is... Condescending and completely out of line with what I have grown used to in my years using Linux. First, there is so much simplistic self-praise sprinkled throughout it. There is almost no page I landed on that does not mention how user-friendly and user-centric Docker's commandline arguments are — They let you talk in almost plain1 English. What they don't mention is that... Well, that's the way of basically every command-line tool. Of course, as soon as you start specifying details to it, the plain-Englishness starts dilluting into a more realistic English-inspiredness...
Then... Things that go against our historical culture. It is often said that Windows documentation tends to be repetitive because users don't have the patience to read a full document. And our man pages are succint and to the point, because in our culture it is expected that users know how to search for the bit of information they are after. But reading documentation that's so excited with itself and praises again and again the same values and virtues, but never gets to the point I am interested in getting at (be it deployment, interoperation, description of the in-disk images+overlays layout, or anything moderately technical) never gets there... makes me quite unhappy.
Last (for now)... Such a continuous sales pitch, an insistence on the good virtues, makes me wary of something they might be hiding.
Anyway, at least for now, I just wanted to play a bit with it; I will wait at least until there is a backport to the stable Debian version before I consider moving my LXC VMs setup over to Docker (and a backport does not seem trivial to achieve, as Docker has several updated low-level dependencies we are unlikely to see in Wheezy).
But I had to vent this. OK, now go back to your regular work ;-)
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