Monday, May 23, 2005

Paus i arbetet

Morsning.
Jag satt precis och kompilerade LAM, da det plotsligt klev in fyra arbetare pa kontoret. De hade med sig kontorsmobler, verktyg och maskiner och skulle bygga ngt; det kandes lite som i bathytt-scenen i "A night at the opera", nar det kliver in en massa manniskor i en liten bathytt. Nastan omgaende stod det klart att jag inte kunde besvara ngn av deras fragor, och att de inte fattade att jag inte inte fattade ngt alls, men vi lyckades komma overens om att de skulle ringa 9575 och prata med Shiwu. Dock sa fann jag det nodvandigt att lamna rummet eftersom hantverkare med borrmaskiner for mer ovasen an dator-servrar, sa nu sitter jag har istallet.

Den senaste tiden jag har jag fepplat med drivrutiner som jag forsokt fa att fungera ihop med var linux-distro of choice, men efter att ha bollat med kallkod och karn-moduler nagra dagar, sa bestammde jag att det projektet lag utanfor min tidsram, och valde distro alternativ 2, FC3. Har fungerade det utan krangel, bara att patcha karnan och kompilera om med en annan kompilator.

En grov uppskattning av out-of-the-box-prestandan pa (seriell) VASP var mojligtvis inte sa imponerande, ca 4.5 ggr snabbare an pa min 866 MHz PIII (lankade med intel math kernel library), sa det blir till att fippla lite med olika BLAS-bibliotek, och fixa ett ordentligt test-system och se om man kan battra pa prestandan lite. Jag aterkommer med lite MFLOPS-siffror nar jag kollat lite noggrannare och undersokt hur det skalar med flera processorer.

ha're

/m

6 Comments:

Blogger Kent Brockman said...

Sicken scenförändring. Från turistaktiga betraktelser till datageek-rabblande av siffror. :)

4:02 AM  
Blogger [cmh] said...

Jahapp, så blev det en rapport från planeten Zerblatt. Distro-hopp blas fork foo bar. Urk pipe gnervit. MFLOPS!

7:34 AM  
Blogger Unknown said...

Första stycket: Jag gillar bathyttsscenen!

Andra stycket: okej... han patchar kärnan...

Tredje stycket: Nämenvafan!!!!

8:05 AM  
Blogger hilbert said...

Kinesisk parlör:

LAM/MPI is a high quality implementation of the Message Passing Interface (MPI) Standard. LAM/MPI provides high performance on a variety of platforms, from small off-the-shelf single CPU clusters to large SMP machines with high speed networks, even in heterogenous environments. In addition to high performance, LAM provides a number of usability features key to developing large scale MPI applications.

Kernel modules. What exactly is a kernel module? Modules are pieces of code that can be loaded and unloaded into the kernel upon demand. They extend the functionality of the kernel without the need to reboot the system. For example, one type of module is the device driver, which allows the kernel to access hardware connected to the system. Without modules, we would have to build monolithic kernels and add new functionality directly into the kernel image. Besides having larger kernels, this has the disadvantage of requiring us to rebuild and reboot the kernel every time we want new functionality.

FC3. Fedora Core 3 is now available from Red Hat and at distinguished mirror sites near you, and is also available in the torrent. Fedora Core has expanded in this release to four binary ISO images and four source ISO images, and is available for both x86-64 and i386.

Kernel patches. As indicated by the name a patch is something that repairs a hole. A newly released kernel might not work as good as was intended with a certain hardware, and to fix that, instead of releasing a whole new kernel, a kernal patch is released.

The BLAS (Basic Linear Algebra Subprograms) are high quality "building block" routines for performing basic vector and matrix operations. Level 1 BLAS do vector-vector operations, Level 2 BLAS do matrix-vector operations, and Level 3 BLAS do matrix-matrix operations. Because the BLAS are efficient, portable, and widely available, they're commonly used in the development of high quality linear algebra software, LINPACK and LAPACK for example.

VASP is a complex package for performing ab-initio quantum-mechanical molecular dynamics (MD) simulations using pseudopotentials or the projector-augmented wave method and a plane wave basis set. The approach implemented in VASP is based on the (finite-temperature) local-density approximation with the free energy as variational quantity and an exact evaluation of the instantaneous electronic ground state at each MD time step. VASP uses efficient matrix diagonalisation schemes and an efficient Pulay/Broyden charge density mixing.

FLOPS. Short for floating-point operations per second, a common benchmark measurement for rating the speed of microprocessors. Floating-point operations include any operations that involve fractional numbers. Such operations, which take much longer to compute than integer operations, occur often in some applications. A megaFLOPS (MFLOPS) is equal to one million floating-point operations per second, and a gigaFLOPS (GFLOPS) is equal to one billion floating-point operations per second. A teraFLOPS (TFLOPS) is equal to one trillion floating-point operations per second.

3:42 AM  
Blogger hilbert said...

Driftwood finishes ordering from the steward and steps back into his cabin, closing the door.
Driftwood: Well that's fine. If that steward is deaf and dumb, he'll never know you're in here.
Fiorello: Why sure, that's all right...
(A knock on the door)
Driftwood: Yes?
Chambermaid: We've come to make up your room.
Fiorello: Are those my hard boiled eggs?
Driftwood: I can't tell until they get in the room. Come on in, girls, and leave all hope behind. But you've gotta work fast 'cause you've gotta get out in ten minutes...
Fiorello: Hey, Tomasso. Wake up. They're gonna fix the beds...
Driftwood (to the chambermaids): Say, I'd like two pillows on that bed there, huh?
(As the chambermaids struggle to get to the beds, Tomasso in his semi-conscious state begins to drape himself over the chambermaids.)
Driftwood (to Fiorello) Hey, there's a slight misunderstanding here. I said the girls had to work fast - not your friend.
Fiorello: He's still asleep...
Driftwood: You know he does better asleep than I do awake?
Fiorello: Yeah, he always sleeps that way. Now he's half asleep.
Driftwood: Yes, he's half asleep and half nelson...
(A knock at the door)
Driftwood: Yes?
Engineer: I'm the engineer. I'm here to turn off the heat.
Driftwood: Well, you can start right in on him.
Fiorello: Wake up, Tomasso... Tomasso, we're a gonna eat soon...
Driftwood: You know, if it wasn't for Gottlieb, I wouldn't have got this room? (a knock on the door) Just hold him there a second...
Manicurist: Did you want a manicure?
Driftwood: No, come on in! I hadn't planned on a manicure, but I think on a journey like this, you ought to have every convenience you can get... (Tomasso's foot gets in the way of the manicurist). Hey, listen, I'm getting the manicure. Get out of here, will ya?
Manicurist: Did you want your nails long or short?
Driftwood: You'd better make 'em short. It's getting kind of crowded in here. I don't know. This isn't the way I pictured an ocean voyage. I always visualized sitting in a steamer chair with a steward bringing me bouillon. You couldn't get any bouillon in here unless they brought it in through a keyhole.
(A knock at the door)
Engineer's assistant: I'm the engineer's assistant.
Driftwood: You know, I had a premonition you were going to show up. The engineer's right over there in the corner. You can chop your way right through... Say, is it my imagination or is it getting crowded in here?
Fiorello: I've got plenty of room...
(A knock at the door)
Driftwood: Yes?
Woman: Is my Aunt Minnie in here?
Driftwood: Well, you can come in and prowl around if you wanna. If she isn't in here, you can probably find somebody just as good...
Woman: Well, can I use your phone?
Driftwood: Use the phone?! I'll lay ya even money you can't get in the room! This boat will be in New York before you can get to that phone...
(A knock at the door)
Cleaning lady: I came to mop up.
Driftwood: Just the woman I'm looking for. Come right ahead. You'll have to start on the ceiling. It's the only place that isn't being occupied... (knock at the door) Tell Aunt Minnie to send up a bigger room, too, will ya? (knocking again)
Steward: Stewards...
Driftwood: Ah, come right in!
Fiorello: Hey, Tomasso, the food! The food!
Driftwood: I've been waiting all afternoon for you stewards...
(The stewards crowd into the room as Tomasso dives onto the trays in his semi-conscious state. The next visitor is none other than Mrs. Claypool, who after knocking on the door, finds the cabin suddenly bursting open as people cascade into the ship's hallway.)

4:07 AM  
Blogger hilbert said...

Tuff tysk forskning:
Hur testar man den mekaniska smärttröskeln i ansiktet? Ett karateslag eller ett boxarslag?


"We have compiled a comprehensive QST protocol as part of the German Research Network on Neuropathic Pain (DFNS) using well established tests for nearly all aspects of somatosensation. This protocol encompasses thermal as well as mechanical testing procedures. Our rationale was to test for patterns of sensory loss (small and large nerve fiber functions) or gain (hyperalgesia, allodynia, hyperpathia), and to assess both cutaneous and deep pain sensitivity. The practicality of the QST protocol was tested in 18 healthy subjects, 21–58 years, half of them female. All subjects were tested bilaterally over face, hand and foot. We determined thermal detection and pain thresholds including a test for the presence of paradoxical heat sensations, mechanical detection thresholds to von Frey filaments and a 64-Hz tuning fork, mechanical pain thresholds to pinprick stimuli and blunt pressure, stimulus–response-functions for pinprick and dynamic mechanical allodynia (pain to light touch), and pain summation (wind-up ratio) using repetitive pinprick stimulation."

10:15 AM  

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