Mathematical & Computer Sciences

OS Projects :: RE: Project2 | How to receive the output from the fetch script

Jeremy Norman — Tue, 07 Oct 2008 07:22:11 GMT

Author: Jeremy Norman
Posted: Tue Oct 07, 2008 1:22 am (GMT -6)

Justin,

If you have a directory that was given from the command line options, then don't bother reading from standard in.

Otherwise, you are free to provide a prompt so that a human at the terminal knows why it is waiting (type in a directory). The prompt will obviously be ignored by a piped program and have no affect except for usability.

OS Projects :: RE: Project2 | How to receive the output from the fetch script

Justin Guerra — Tue, 07 Oct 2008 06:04:11 GMT

Author: Justin Guerra
Posted: Tue Oct 07, 2008 12:04 am (GMT -6)

Is there a way to check that there actually is stdin? Currently if I pipe info my script runs fine, but if I don't pipe something in it gets stuck.

Concepts, Projects, and Lounge :: RE: Reversi Questions

apryce — Tue, 07 Oct 2008 03:44:14 GMT

Author: apryce
Subject: Bug found?
Posted: Mon Oct 06, 2008 9:44 pm (GMT -6)

I believe I may have found a bug. This occurs when reversi.cpp when checkSquares is called. I believe that it is occurring because at line 282 -1 is passed to checkSquares which uses unsigned char which goes from 0-255 so a -1 effectively rolls back to 255. This is used as a reference to a square on the board in getSquare a few lines later resulting in an exception. I have a screen-shot, but don't know how to attach it here.

Adam

Edit: I tried modifying this call so that it took arguments of int (to handle -1) and then modified

unsigned char row = (unsigned char)((int)getRow() + rIncr);
unsigned char col = (unsigned char)((int)getCol() + cIncr);
if(!(row<boardSize && col<boardSize))
return false;

This doesn't help though because row is incremented to 8 around line 255. Then isLegal is called however isLegal doesn't check whether a move is in the bounds of the board.

isLegal is used in key circumstances, so I am hesitant to assume a simple if statement will not have other affects on the logic. Ed, as designer if you get a chance to look at this it would be very helpful.

Toilers :: RE: Fall 2008: Toiler Meetings

amunjal — Tue, 07 Oct 2008 02:33:40 GMT

Author: amunjal
Subject: Handout posted
Posted: Mon Oct 06, 2008 8:33 pm (GMT -6)

I have posted the handout for the coming Toilers talk on the twiki home page.

Concepts, Projects, and Lounge :: RE: Reversi Questions

apryce — Tue, 07 Oct 2008 02:31:32 GMT

Author: apryce
Subject: Unable to extract archive
Posted: Mon Oct 06, 2008 8:31 pm (GMT -6)

I am unable to extract the 'tgz' level of the reversi.tgz.gz
I am using Winzip 11.2
Is there a free windows based archiver that anybody has had luck with?

Adam

Edit: looking more closely on the BB assignment it is listed as reversi.tgz, but when Chrome downloads it becomes reversi.tgz.gz

SOLUTION: Chrome is adding an extra .gz in the name which confuses winzip. Just remove the .gz from the name and you can extract it.

Concepts, Projects, and Lounge :: RE: Reversi Questions

apryce — Tue, 07 Oct 2008 01:41:20 GMT

Author: apryce
Subject: Error in project doc
Posted: Mon Oct 06, 2008 7:41 pm (GMT -6)

I believe player and score should be reversed in the following from page 6

Quote:

typename Game::Score The type of the player number reported
by getScore
typename Game::Player The type of the score reported by
getPlayer

OS Projects :: RE: Data collection question

Chris Walsh — Tue, 07 Oct 2008 00:00:04 GMT

Author: Chris Walsh
Posted: Mon Oct 06, 2008 6:00 pm (GMT -6)

Here's a new architecture that just hit me that removes the monolithic element but still allows you to do in-line manipulation. With this way you keep modularity too!

Code:

CMD_ONE="commands | commands"
CMD_TWO="commands | commands"
CMD_THREE="commands | commands"
ssh host "$CMD_ONE; $CMD_TWO; $CMD_THREE" redirect into $HOST_FILE

Quote:

The question that matters to me right now is: will I lose points for keeping it as one command?

EDIT: You made such a good point that I'm trying to get Tracy to make an announcement that you shouldn't do a monolithic approach BUT remote manipulation is OK. So if she makes the in-class announcement than yes you'll lose points... if not, I think you're okay.

Try and spread the word for those that don't check Ore frequently if you could, Ben - as the handout was a bit ambiguous. Thanks

(Huzzah I hit post #50!)

OS Projects :: RE: Data collection question

benjones — Mon, 06 Oct 2008 20:52:53 GMT

Author: benjones
Posted: Mon Oct 06, 2008 2:52 pm (GMT -6)

I think that it makes sense to do at least some of the processing in the ssh command, like when I count processes:

Code:

ps ax | wc -l

Listing all the running processes would take a lot more network bandwith than printing "120". I think there are valid points for both approaches. The question that matters to me right now is: will I lose points for keeping it as one command?

Thanks
-Ben

Concepts, Projects, and Lounge :: RE: Schedule

ekrohne — Mon, 06 Oct 2008 19:56:51 GMT

Author: ekrohne
Posted: Mon Oct 06, 2008 1:56 pm (GMT -6)

Here you go.

Lab 2 due: Midnight Tuesday, 10/14
Midterm: Friday, 10/17
Final project 1st deliverable: Midnight Sunday, 10/26

Also, blackboard was wrong before. It used to say 10/12; I've just fixed it.
_________________
"8:14; Press Return"
-- Darren Aronofsky, Pi

"Watch me set my pants on fire!"
-- Fred Gallagher, Megatokyo

Concepts, Projects, and Lounge :: RE: Schedule

Jeremy Norman — Mon, 06 Oct 2008 18:13:06 GMT

Author: Jeremy Norman
Posted: Mon Oct 06, 2008 12:13 pm (GMT -6)

So as stated again in class, for sure reversi is due on 10/14/08 (I think even blackboard had that)...

So still interested in the next deadline: final project check-point deliverable.

Concepts, Projects, and Lounge :: Schedule

Jeremy Norman — Mon, 06 Oct 2008 17:29:04 GMT

Author: Jeremy Norman
Subject: Schedule
Posted: Mon Oct 06, 2008 11:29 am (GMT -6)

Ed,

I cannot remember exactly how everything is working out for dates in the next few weeks. I think that it was decided that the reversi agent will be done a week from tomorrow, and sometime after that is our first deliverable.

Can you put specific dates here on ore (in response to this). That way we don't need to bring it up in class again and also in an easy to reference place?

Concepts, Projects, and Lounge :: RE: Reversi Questions

ekrohne — Mon, 06 Oct 2008 17:03:25 GMT

Author: ekrohne
Posted: Mon Oct 06, 2008 11:03 am (GMT -6)

You can assume moves your agent receives are valid. If the referee gives your agent an illegal move, and you make an illegal move (or a non-move) based on it, then it won't count against you in any way. The referee will keep track of and store a game log that we can analyze later to determine what went wrong. I'll verify whose fault it is if anyone gets disqualified.
_________________
"8:14; Press Return"
-- Darren Aronofsky, Pi

"Watch me set my pants on fire!"
-- Fred Gallagher, Megatokyo

OS Projects :: Project 2 | Loadavg

Mark Godwin — Mon, 06 Oct 2008 01:24:50 GMT

Author: Mark Godwin
Subject: Project 2 | Loadavg
Posted: Sun Oct 05, 2008 7:24 pm (GMT -6)

For those of you curious... I found this text on /proc/loadavg that helps explain what the numbers mean exactly.

Quote:

The load average equals the average of the number of tasks running or in
a runnable state at any instant, as opposed to zombie tasks, tasks
waiting on an operation such as I/O, suspended tasks, etc. The three
different numbers represent that average as measured over the last
minute, the last five minutes, and the last fifteen minutes,
respectively.

Optimally, then, you want to have the load average stay below the number
of CPUs in your machine. So, on a dual box, it's best if the load
average is below 2.

When the load average goes over the number of CPUs on the system, this
means that there are tasks left sitting and waiting for CPU time. This
may or may not be a problem depending on what the system is doing, how
good the kernel scheduler is, and other things. For example, if you're
running something like distributed.net or SETI@home, your load average
will never go below the number of processes you've got running for those
projects; this isn't a problem because the priority for those tasks is
low and there's no deadline for finishing those tasks.

So there's no magic rule about load averages. You could have two
single-CPU boxes, and the one with a 1.5 load average could perform much
worse than the one with a 4 load average. I've heard of boxes with load
averages in the three-digit range (before the decimal) that are still
usable.

Incidentally, the same information that's displayed in /proc/loadavg is
also displayed with the "uptime" command; the output from that command
is pretty standard, so your code will be more portable if you parse
uptime's output instead of parsing /proc/loadavg.

from http://www.luci.org/luci-discuss/200210/msg00055.html

OS Projects :: RE: Project2 | How to receive the output from the fetch script

Alan Rowe — Mon, 06 Oct 2008 01:10:54 GMT

Author: Alan Rowe
Posted: Sun Oct 05, 2008 7:10 pm (GMT -6)

Or, you can use the command 'read'.

OS Projects :: RE: Data collection question

Chris Walsh — Mon, 06 Oct 2008 00:51:53 GMT

Author: Chris Walsh
Posted: Sun Oct 05, 2008 6:51 pm (GMT -6)

Hey Ben,

I think that it would be a better design (even though you make a good point about the network traffic) to keep it simple. Just like one of the tenets of shell scripting; things that do only one thing but do it well.

Code:

x=`ssh host "run commands ; more commands"`
y=`echo $x | awk stuff`
z=`echo $x | sed stuff`

Another benefit to the design above is that it's modular. Say you want to add more data to the retrieval list - its just a matter of adding on to the first line and then doing your own manipulation as a fourth var after z. It's much more maintainable and readable than your monolithic line approach, imo.

Good job on doing all the commands in one ssh though as opposed to doing one ssh for each command. This keeps the overhead of authentication and handshaking down to a minimum.

Excuse my late response; I've been at a conference in Keystone since Wednesday.

Enjoy!

Concepts, Projects, and Lounge :: Reversi Questions

mbarkmei — Mon, 06 Oct 2008 00:25:20 GMT

Author: mbarkmei
Subject: Reversi Questions
Posted: Sun Oct 05, 2008 6:25 pm (GMT -6)

Are we able to assume that any move given to the agent is a valid move, or should we check for it being valid?

OS Projects :: RE: Project2 | How to receive the output from the fetch script

Curtis Fleming — Sun, 05 Oct 2008 21:37:41 GMT

Author: Curtis Fleming
Subject: Using Pipe
Posted: Sun Oct 05, 2008 3:37 pm (GMT -6)

So given this pseudo-code example

fetchScript | publishScript

Inside of your publishScript you can access what fetchScript outputed by cat-ing the file /dev/stdin

so

Code:

# In the publishScript I need to read something from the Standard In pipe
myVariable=`cat /dev/stdin/`

where all of the output from fetchScript is read in as a single line into myVariable
In other words, if fetchScript echoed out

apples are red
Some other text

then myVariable in your publishScript with have the value
apples are red Some other text

OS Projects :: RE: Project2 | How to receive the output from the fetch script

songliu — Sun, 05 Oct 2008 20:43:31 GMT

Author: songliu
Posted: Sun Oct 05, 2008 2:43 pm (GMT -6)

yes, but the sentry script will print out the directory on stdout
so, how to use it (directory on stdout) in publish script?

OS Projects :: RE: On alamode versus "on" alamode

Jeremy Norman — Sun, 05 Oct 2008 03:20:45 GMT

Author: Jeremy Norman
Posted: Sat Oct 04, 2008 9:20 pm (GMT -6)

Doug is right.

While in class the other day, many people sshed onto alamode itself to run their scripts rather than running them locally. This is also true for many that were using their own computers for the project.

So... make sure your prompt says username@labmachine$ when you run your program. DO NOT run when your prompt says username@alamode$

OS Projects :: RE: On alamode versus "on" alamode

Doug Welch! — Sat, 04 Oct 2008 23:14:22 GMT

Author: Doug Welch!
Posted: Sat Oct 04, 2008 5:14 pm (GMT -6)

I believe that Jeremy means that if you log in remotely (which has to be done though alamode) that you should ssh into another machine so that you arent using alamode to run your scripts

The commands will then be passed through alamode then executed on the machine that you ssh into and alamode just has to worry about managing the remote connection

what computer you ssh into may be easier to pick if you know the loads on the computer ...

OS Projects :: RE: On alamode versus "on" alamode

Curtis Fleming — Sat, 04 Oct 2008 21:10:38 GMT

Author: Curtis Fleming
Subject: Question
Posted: Sat Oct 04, 2008 3:10 pm (GMT -6)

Do you mean don't profile all of the computers in alamode often because it is too taxing ssh-ing around?

OS Projects :: On alamode versus "on" alamode

Jeremy Norman — Sat, 04 Oct 2008 14:42:33 GMT

Author: Jeremy Norman
Subject: On alamode versus "on" alamode
Posted: Sat Oct 04, 2008 8:42 am (GMT -6)

I meant to make an announcement during class the other day.

Please do not actually run your scripts on alamode itself. Alamode is used to help coordinate the lab and is a SHARED resource. That means you should use it for as little as you can afford.

Instead, make sure to run your scripts from a specific lab machine. http://ore.mines.edu/phpBB/viewtopic.php?t=3657

Concepts, Projects, and Lounge :: RE: Study Group Sign up and Dates (Do the right thing!)

abarman — Sat, 04 Oct 2008 02:18:33 GMT

Author: abarman
Posted: Fri Oct 03, 2008 8:18 pm (GMT -6)

Sweet, I hope people go there on tuesday too. unfortunately I have class during that time on Tuesday. But I will be at Van Deuker Lounge 6 to 10 doing Comp Org in the evenings

OS Projects :: RE: Project2 | How to receive the output from the fetch script

benjones — Fri, 03 Oct 2008 15:17:32 GMT

Author: benjones
Posted: Fri Oct 03, 2008 9:17 am (GMT -6)

The alamode-sentry script is supposed to print out the directory it saved stuff to.

-Ben

OS Concepts :: Review Question 4.6

songliu — Fri, 03 Oct 2008 05:17:56 GMT

Author: songliu
Subject: Review Question 4.6
Posted: Thu Oct 02, 2008 11:17 pm (GMT -6)

List three advantages of ULTs over KLTs.

1. The cost of threads swithing is small

2. Threads can be scheduled acording to particular needs

3. ULTs can run on any OS