Re: cat command with timeout
Years ago I needed a cat with a timeout argument. I modified the cat code. It was very easy (if I remember correctly less than one hour of work). Sadly, I don't have the code. Good luck. Dan 2010/6/10 Ori Idan o...@helicontech.co.il I have to read lines from serial port, I thought to read them using 'cat' however, since the other unit connected to the serial port, might malfunction and not send anything, I need a timeout to stop reading after few seconds. Does someone know of an alternative to cat with timeout? -- Ori Idan ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
GoogleCL
Heh-heh, for those of you guys and gals who love both Google apps and command line (and I suspect there are a few here) here is a bit of code annouced yesterday (?): http://code.google.com/p/googlecl/ I don't use Google apps myself and I have not tried it, but it looks darn useful if you do, so I thought I'd post. Curiosity: can someone report if this works from Androids and/or other Linux phones? -- Oleg Goldshmidt | p...@goldshmidt.org ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
Re: platform for number crunching---resume
There is always another option,... one other option would be to underclock your CPUs and then even when they hit the 100% usage over long periods as it is running at lower speed, it wouldn't heat that much. On Sat, Jun 19, 2010 at 11:12 AM, Shimon Panfil i...@industrialphys.comwrote: Many thanks for everybody who answered my question. Short resume is following: 1. x86_64 is really the only affordable platform( sure it depends on definition of affordable but anyway people got it right); 2. Good idea is cleaning off the dust from the box and check thermal paste; 3. Is the problem specific to my machine or has general nature still unclear, since: a) gamers forums are full of complaints about overheating; b) nobody provides example of heavy *numerical* load without overheating, kernel compilation for example is not relevant becouse AFAIK compiler does not use floating point calculations and power consumption and heating may be essentially different; 4. All the subject of CPU power consumption and heating is complicated and needs serious investigation. Most of the references I've seen are of anecdotal character, very little reliable physical/engineering information. Probably manufacturers prefer to keep this information for own use. S. -- Shimon Panfil: Industrial Physics and Simulations http://industrialphys.com ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
Re: platform for number crunching---resume
On Jun 20, 2010, at 11:48 AM, Meir Michanie wrote: There is always another option,... one other option would be to underclock your CPUs and then even when they hit the 100% usage over long periods as it is running at lower speed, it wouldn't heat that much. The problem with that is the whole system is desinged to be run at about 85% useage. Beyond that everything overheats, electrical signals interfere with each other, etc. 100% is ok for peaks, but if the system runs like that for days, it's going to fail. Even if you were to add better cpu cooling, replace passive heat sinks on other chips with active ones, and so on. Attempts at using commerical game systems such as the PS/3 for compute farms did not do well. The first version was fine, but the latest slim one can't sustain high cpu rates, which is one reason Sony dropped (with a loud thud) Linux on them. Geoff. -- geoffrey mendelson N3OWJ/4X1GM Jerusalem Israel geoffreymendel...@gmail.com I do multitasking. If that bothers you, file a complaint and I will start ignoring it immediately. ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
Perl and integer overflows
Hi all, I'm trying to calculate the result of a string hash function in perl. I need an explicit function, as the perl output is used to create a C program, that will then use that very same hash function. Please, do not direct me to perl's excellent hash handling. I know it's there. I use it where applicable. This is not one of those cases. The hash function I'm using is sdbm hash function (http://www.cse.yorku.ca/~oz/hash.html). To calculate it, I need to perform integer arithmetics, knowing full well it may overflow. It is okay for it to overflow, as I only need the bottom 32 bits. In fact, my code ANDs the result with 0x, to make sure that, on 64 bit platforms, I only get the bottom 32 bits. Here's the problem. When the integer gets too big, Perl replaces it with MAXINT. On 64 bit platforms, that's not too bad - I can simply truncate to 32 bits after each operation. On 32 bit platforms, I'm a bit at a loss as to what to do. Any suggestions on how to get the C integer semantics out of perl? Shachar -- Shachar Shemesh Lingnu Open Source Consulting Ltd. http://www.lingnu.com ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
Re: Perl and integer overflows
On Sunday 20 June 2010 13:25:00 Shachar Shemesh wrote: Hi all, I'm trying to calculate the result of a string hash function in perl. I need an explicit function, as the perl output is used to create a C program, that will then use that very same hash function. Please, do not direct me to perl's excellent hash handling. I know it's there. I use it where applicable. This is not one of those cases. The hash function I'm using is sdbm hash function (http://www.cse.yorku.ca/~oz/hash.html). To calculate it, I need to perform integer arithmetics, knowing full well it may overflow. It is okay for it to overflow, as I only need the bottom 32 bits. In fact, my code ANDs the result with 0x, to make sure that, on 64 bit platforms, I only get the bottom 32 bits. Here's the problem. When the integer gets too big, Perl replaces it with MAXINT. On 64 bit platforms, that's not too bad - I can simply truncate to 32 bits after each operation. On 32 bit platforms, I'm a bit at a loss as to what to do. Any suggestions on how to get the C integer semantics out of perl? I'd google for perl long long # Shachar ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
interesting tidbit about overheating
Mechanical engineers are involved in the design of boards too! How? When boards are heated everything tends to expand and guess what, the expansion factor is not the same for the comments, the traces, etc. Multiple layer boards are designed so that things melt at different temperatures -- guess what that means on top of everything -- the board itself is made of layers and the layers and components (traces, holes, etc) all expand at different rates. Engineers need not only work with the temperature range effects but also the duty cycle. Running a cache hot say, with a hit rate of say 97% vs. the design rating of 90% means not only do the chips run hot, but the board is getting stressed. So when an engineer calculates how much solder and what kind of solder based on a 90% hit rate, guess what happens when you hand tune the computations to hit the cache more often -- yep, mechanical stress failures. All this of course comes from the bell-curve. When you design around the center and then add a 50% safety factor, you're not really +2 standard deviations to the right; and that's what you need to know: what is the safety margin in the design, how close to it are you (or equivalently, how far to the right). More interestingly. Chip manufactures produce chips and then sort them at the end. The sort operation sorts chips by the highest clock frequency they run. I.e., a 1 GHz and 1.5 GHz processor have the same design are made the same way, etc. At the end of the manufacturing cycle, the chips are tested and then sorted. Of course the sorting is statistical and need to be biased to the left so that it's pretty good odds that whatever chip you buy can run at a higher clock rate, but it will run hotter (maybe even significantly so, hence the sort operation putting it in a slow bucket), stress your boards, etc. Well, I hope this tidbit is enlightening even though it offers no advice. Shlomo ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
Re: cat command with timeout
You can use timeout command, like timeout 5 cat ... Yigal --- On Sat, 6/19/10, Dan Bar Dov bar...@gmail.com wrote: From: Dan Bar Dov bar...@gmail.com Subject: Re: cat command with timeout To: Ori Idan o...@helicontech.co.il Cc: IGLU Mailing list linux-il@cs.huji.ac.il Date: Saturday, June 19, 2010, 11:03 PM Years ago I needed a cat with a timeout argument.I modified the cat code. It was very easy (if I remember correctly less than one hour of work). Sadly, I don't have the code. Good luck.Dan 2010/6/10 Ori Idan o...@helicontech.co.il I have to read lines from serial port, I thought to read them using 'cat' however, since the other unit connected to the serial port, might malfunction and not send anything, I need a timeout to stop reading after few seconds. Does someone know of an alternative to cat with timeout? -- Ori Idan ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il -Inline Attachment Follows- ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
Re: Perl and integer overflows
On Sunday 20 Jun 2010 13:25:00 Shachar Shemesh wrote: Hi all, I'm trying to calculate the result of a string hash function in perl. I need an explicit function, as the perl output is used to create a C program, that will then use that very same hash function. Please, do not direct me to perl's excellent hash handling. I know it's there. I use it where applicable. This is not one of those cases. The hash function I'm using is sdbm hash function (http://www.cse.yorku.ca/~oz/hash.html). To calculate it, I need to perform integer arithmetics, knowing full well it may overflow. It is okay for it to overflow, as I only need the bottom 32 bits. In fact, my code ANDs the result with 0x, to make sure that, on 64 bit platforms, I only get the bottom 32 bits. Here's the problem. When the integer gets too big, Perl replaces it with MAXINT. On 64 bit platforms, that's not too bad - I can simply truncate to 32 bits after each operation. On 32 bit platforms, I'm a bit at a loss as to what to do. You can compile Perl with 64-bit integers, even on 32-bit platforms. That or use a big-integer module such as Math::BigInt : http://perldoc.perl.org/Math/BigInt.html See its lib = 'GMP' option if you want much better speed. Regards, Shlomi Fish -- - Shlomi Fish http://www.shlomifish.org/ What does Zionism mean? - http://shlom.in/def-zionism God considered inflicting XSLT as the tenth plague of Egypt, but then decided against it because he thought it would be too evil. Please reply to list if it's a mailing list post - http://shlom.in/reply . ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
Re: cat command with timeout
watch -n1 cat lala is another possiblity 2010/6/20 Yigal Asnis yigalas...@yahoo.com You can use timeout command, like timeout 5 cat ... Yigal --- On *Sat, 6/19/10, Dan Bar Dov bar...@gmail.com* wrote: From: Dan Bar Dov bar...@gmail.com Subject: Re: cat command with timeout To: Ori Idan o...@helicontech.co.il Cc: IGLU Mailing list linux-il@cs.huji.ac.il Date: Saturday, June 19, 2010, 11:03 PM Years ago I needed a cat with a timeout argument. I modified the cat code. It was very easy (if I remember correctly less than one hour of work). Sadly, I don't have the code. Good luck. Dan 2010/6/10 Ori Idan o...@helicontech.co.ilhttp://mc/compose?to=...@helicontech.co.il I have to read lines from serial port, I thought to read them using 'cat' however, since the other unit connected to the serial port, might malfunction and not send anything, I need a timeout to stop reading after few seconds. Does someone know of an alternative to cat with timeout? -- Ori Idan ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mc/compose?to=linux...@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il -Inline Attachment Follows- ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mc/compose?to=linux...@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
Re: Perl and integer overflows
Shlomi Fish wrote: You can compile Perl with 64-bit integers, even on 32-bit platforms. That or use a big-integer module such as Math::BigInt : http://perldoc.perl.org/Math/BigInt.html Thanks. I'll give it a try. Shachar See its lib = 'GMP' option if you want much better speed. Regards, Shlomi Fish -- Shachar Shemesh Lingnu Open Source Consulting Ltd. http://www.lingnu.com ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
Re: cat command with timeout
On Sun, Jun 20, 2010 at 04:06:51PM +0300, Raz wrote: watch -n1 cat lala is another possiblity What for? This re-runs cat 1 second after it has finished running. Try: watch -n1 'sleep 5; echo hi' It will refresh the display every 6 seconds. -- Tzafrir Cohen | tzaf...@jabber.org | VIM is http://tzafrir.org.il || a Mutt's tzaf...@cohens.org.il || best tzaf...@debian.org|| friend ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
Re: Just for giveaway and/or trade
If you are nice, I want one and one thing only in trade - a vacuum handle for computer room tiles. One. C'est touts. Hi Marc. What is special about such a vacuum handle? I have lots of junk and I'm pretty sure that there are some vacuum cleaner accessories at my mother in law's place. What makes computer room tiles special such that they need a specialized vacuum handle, and how can I tell that I have such a handle? -- Dotan Cohen http://gibberish.co.il http://what-is-what.com ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
Re: platform for number crunching---resume
On Sat, Jun 19, 2010, Shimon Panfil wrote about platform for number crunching---resume: b) nobody provides example of heavy *numerical* load without overheating, kernel compilation for example is not relevant becouse AFAIK compiler does not use floating point calculations and power consumption and heating may be essentially different; The key phrase in the above sentence is may be. Do you have any reason to suspect why floating-point calculation take significantly more energy than integer calculations (and all the other things that go on, including memory refresh, and what have you)? Have you actually measured such a difference? I didn't, so I'm only guessing here, but my guess is that there may be a difference between the exact energy use of a tight FPU calculation loop and a tight integer calculation (or kernel compilation, or whatever), but I doubt it's a really significant different to the point of making a difference between a perfectly functioning 8-CPU machine and the heat-death of a 2-CPU machine... -- Nadav Har'El| Sunday, Jun 20 2010, 9 Tammuz 5770 n...@math.technion.ac.il |- Phone +972-523-790466, ICQ 13349191 |This message contains 100% recycled http://nadav.harel.org.il |characters. ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
Re: Just for giveaway and/or trade
:) it is handle to pick up computer room floor tiles. Looks like a phone hand-set. Marc On Jun 20, 2010, at 8:17 PM, Dotan Cohen wrote: If you are nice, I want one and one thing only in trade - a vacuum handle for computer room tiles. One. C'est touts. Hi Marc. What is special about such a vacuum handle? I have lots of junk and I'm pretty sure that there are some vacuum cleaner accessories at my mother in law's place. What makes computer room tiles special such that they need a specialized vacuum handle, and how can I tell that I have such a handle? -- Dotan Cohen http://gibberish.co.il http://what-is-what.com Marc Volovic marcvolo...@me.com ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
Re: Just for giveaway and/or trade
On 20 June 2010 20:41, Marc Volovic marcvolo...@me.com wrote: :) it is handle to pick up computer room floor tiles. Looks like a phone hand-set. Ah, that thing! No, I have none of those, sorry! Have a great week. -- Dotan Cohen http://gibberish.co.il http://what-is-what.com ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
Re: Just for giveaway and/or trade
On 20/06/2010 19:17, Dotan Cohen wrote: If you are nice, I want one and one thing only in trade - a vacuum handle for computer room tiles. One. C'est touts. Hi Marc. What is special about such a vacuum handle? I have lots of junk and I'm pretty sure that there are some vacuum cleaner accessories at my mother in law's place. What makes computer room tiles special such that they need a specialized vacuum handle, and how can I tell that I have such a handle? Well, If you have a puck, it's a great paddle for air hokey ! -- Moish ___ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
