Monday, November 8, 2010

Pipeline revisited

  1. We talked a big deal about our old friend the Pipeline. And we discovered something fairly counterintuitive, with the Pipelining technique we increase the cycles per instruction... how's that? well, in inserting new registers and specialized units within the process makes synchronization and communication a bit more complicated introducing some overhead with every level of complexity of pipelining. Ha ha, but what's the catch? Very simple indeed, instructions overlap all the way through the pipeline, so this extra overhead is compensated with the fact that the overall set of instructions used in our program finish more quickly, than if we weren't using pipeline.

  2. The last class before today (I didn't feel like blogging), we, I mean, I learned , because it was a concept that our dear teacher taught them in the modern operating systems class, the concept of sub-dividing the cache memory in two sections, one for data exclusively and one for instructions. This is due to the fact that when an area of the cache is written it's marked as dirty (cute), and that indicates the processor that he must rewrite the corresponding data back to main memory so it's updated, this is true for data but instructions will never be overwritten inside the cache so it makes no sense to mark instructions as dirty. Setting things this way allow for simultaneous writing and reading, using two kinds of i/o ports to the memory.

  3. Today the teacher was jocking around with my dear Rose with the following analogy (she was the only girl in the class today): Imagine you've got to carry 300 glass coke boxes up to a 3rd floor with a little help of your friends, in this case the whole class. So what's the smartest approach?, to let each friend to carry as much of that boxes alone up to the 3rd floor?, that's dumb...anyway Rose couldn't handle more than 3 bottles at a time, how many trips would she make. Laugh out loud the whole class. We men the stronger gender would finish sooner, quite sooner that she I we would watch her together do her trips, while making jokes at her. So it turns out that the best approach is naturally to simulate our precious pipeline, setting ourselves in a queue handling the boxes from one hand to the other, it was kind of obvious but it was a funny analogy. Of course being Rose inside the queue she would move slower compared to us, so she would introduce the so talked extra overhead. Two solutions :kissing the little princess good bye, or just wait it up so the others can rest in the idle time, of course machines don't need rest, so sorry cutie, you've got to go.

  4. In AIO we explore the reach of XML and its shortcomings, our friend Jaime gave a presentation but it could have been better, but he isn't the one to blame. It turns out that WEKA can manage to make Object Oriented Databases, with Relational DB and XML. The shortcomings of XML are that it doesn't have the kind of foundations that Relational DB has, and there's no hope of XML data queries being at least as fast as those made with Relational DB. The same goes for Object Oriented DB, you can forget about complex queries. The foundations of XML --> trees.

  5. In the SD class, we revisited RPC's and rpcgen. We re-analyzed the inner workings of the protocol, the code itself and its idioms, ain't that complicated at a first sight but it has so much more options that those discussed in the class.

  6. Ohh and I learned how to memorize several unrelated items by making up a story. I managed to learn 20 items in order in about 10 minutes, I know yet kind of slow but practice makes master.

  7. Despite my fasting habits, the awful truth is that I'm no loosing weight so need more drastic measures, I'm gonna work my ass off all day by doing exercise like if there's no tomorrow.

  8. I wish I could be someday as excellent, professional, smart and kind as the architect Francisco Mendez is, we met today and gives me a great deal of hope to be acquainted with people like him.

Words of the day:
Klang -> sound
Protokoll -> event log
Zuletzt -> ~~ recently ( I guess)

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