Problem: On Manjaro (ArchLinux) there are only WLAN channels available up to 11, which is US standard, but not European.
I also could see this problem on Linux Mint and Xubuntu, but not on grml. Drivers like b43, broadcom-wl STA firmware could not give me success. What I did, after many tries failed (compiled own regulatory.bin, playing with crda, iw reg set, ...)
Uninstalled some packages:
pacman -Ru crda
pacman -Ru linux318-broadcom-wl
pacman -Ru zd1211-firmware
pacman -Ru wireless-regdb
pacman -Ru ipw2200-fw
pacman -Ru b43-fwcutter
pacman -Ru ipw2100-fw
Removed manjaro hardware config:
mhwd -r pci network-broadcom-wl
lspci -vnn -d 14e4:
... Broadcom Corporation BCM43225 802.11b/g/n [14e4:4357] (rev 01)
...
Kernel driver in use: bcma-pci-bridge
Kernel modules: bcma
iw reg get
global
country 00: DFS-UNSET
(2402 - 2472 @ 40), (6, 20), (N/A)
(2457 - 2482 @ 40), (6, 20), (N/A), PASSIVE-SCAN
(2474 - 2494 @ 20), (6, 20), (N/A), NO-OFDM, PASSIVE-SCAN
(5170 - 5250 @ 160), (6, 20), (N/A), PASSIVE-SCAN
(5250 - 5330 @ 160), (6, 20), (0 ms), DFS, PASSIVE-SCAN
(5490 - 5730 @ 160), (6, 20), (0 ms), DFS, PASSIVE-SCAN
After restart I could see Channel 13 (iwlist scan | grep Channel:)
iwlist chan also shows 13 channels.
Freitag, 25. September 2015
Montag, 6. Juli 2015
E-Mailverschlüsselung mit Thunderbird+Enigmail
E-Mailverschlüsselung für Anfänger ohne viel Schnick-Schnack ;)
«
»
- Thunderbird installieren
[E-Mailprogramm, welches deine E-Mailkonten verwalten wird] - E-Mailkonto anlegen
- Enigmail-Addon installieren
- Thunderbird -> Extras -> Add-ons
- nach Add-on 'Enigmail' suchen und installieren
- Enigmail Einrichtungs-Assistenten durchklicken und dabei
- - automatisch Gpg4Win (eigentliches Verschlüsselungsprogramm) installieren lassen
- - Schlüsselpaar erzeugen - Testkommunikation mit adele@gnupp.de Teil 1
- Testemail zusammen mit eigenem öffentlichen Schlüssel an adele@gnupp.de schicken
- nach ein paar Minuten erhält man verschlüsselte E-Mail, die automatisch entschlüsselt wird - dabei muss die Passphrase eingegeben werden
- Gesamten PGP PUBLIC KEY BLOCK markieren und kopieren
- eben kopierter öffentlicher Schlüssel in Enigmail-Schlüsselverwaltung einfügen per "Bearbeiten->Aus Zwischenablage importieren"
- - für gewöhnlich schickt man sich *.asc Dateien als Anhang, die dann ganz leicht per Rechtsklick importiert werden, ohne dass Text markiert werden muss - Schlüsselverwaltung
- in Schlüsselverwaltung auf importierten Schlüssel doppelklicken, um Schlüssel zu prüfen
- - Fingerabdruck-Zahl muss über einen zweiten Kanal mit dem Eigentümer abgeglichen werden (Telefon, realer Kontakt)
- - bei adele ist das nicht möglich, daher unterschreiben wir mit "Ich habe es nicht überprüft"
- - das Besitzervertrauen regelt die Vertrauenswürdigkeit des anderen Benutzers
- - adele prüft garantiert keine Fingerprints anderer Benutzer, daher in diesem Beispiel "Ich vertraue ihm NICHT" auswählen - Testkommunikation mit adele@gnupp.de Teil 2
- verschlüsselte und unterschriebene E-Mail an adele schreiben
- - Antwort mit verschlüsselter Nachricht von adele erhalten - Verschlüsselte E-Mails standardmäßig unterschreiben
- Extras->Konten-Einstellungen->OpenPGP-Sicherheit
- - Verschlüsselte Nachrichten unterschreiben - Bei verschlüsselten E-Mails mit Anhängen "Jeden Anhang einzeln verschlüsseln und unterschreiben ..." auswählen - dieser Auswahl-Dialog poppt beim Absenden auf
Nicht abgedeckt in diesem Tutorial werden: Keyserver, Experteneinstellungen, manuelle Key-Erstellung, Export von Unterschriften, Sicherheitsoptimierungen, ...
Für tiefergehende Anleitungen und Erklärungen zu gpg verweise ich auf: http://www.hauke-laging.de/sicherheit/openpgp.html
Bei entsprechendem Bedarf folgen ggf. weitere Screenshot-Anleitungen.
Donnerstag, 3. Oktober 2013
Serializing Arrays and Alignment in CUDA
Perhaps you have to deal with message buffers in general or serialized arrays of mixed types, i.e., different arrays packed together into a generic char buffer array on host side and then unpacking on device side again. There you have to take care about aligning the data right, otherwise kernel launches will fail due to misaligned memory accesses. A 64-bit address is only allowed to start at multiples of 8 bytes.
If there is a char array with packed data in this order:
[3x int, 12x double]
... then misalignment takes place. The double starts not at a 64-bit aligned address. Launching a kernel which unpacks the buffer will fail. cuda-memcheck helps you out by this hint:
========= Invalid __global__ read of size 8
========= at 0x00000248 in kernel(char*, unsigned int)
========= by thread (0,0,0) in block (0,0,0)
========= Address 0x500340004 is misaligned
You can place the data in descending order according to the type size:
[12x double, 3x int]
So remember about aligning next time (also pointing at me!).
If you just come here to see some old-fashioned serialization in action, here you get it:
//nvcc -O2 -m64 -gencode arch=compute_30,code=sm_30 mwe_char.cu #include <stdio.h> #include <cuda.h> #include <cuda_runtime_api.h> #include <device_launch_parameters.h> #include <driver_types.h> #define HANDLE_ERROR(err) __handleError(err, __FILE__, __LINE__) #define HANDLE_LAST(msg) __handleLastError(msg, __FILE__, __LINE__) void __handleError( cudaError err, const char *file, const int line ) { if( cudaSuccess != err) { fprintf(stderr, "%s(%i) : Runtime API error %d: %s.\n", file, line, (int)err, cudaGetErrorString( err ) ); exit(-1); } } void __handleLastError( const char *errorMessage, const char *file, const int line ) { cudaError_t err = cudaGetLastError(); if( cudaSuccess != err) { fprintf(stderr, "%s(%i) : CUDA error : %s : (%d) %s.\n", file, line, errorMessage, (int)err, cudaGetErrorString( err ) ); } } /* * */ __device__ __host__ int toBuffer(char* buffer, unsigned var, unsigned long long llvar) { unsigned long long* ptr0 = reinterpret_cast<unsigned long long*>(buffer); unsigned* ptr1 = reinterpret_cast<unsigned*>(buffer+sizeof(unsigned long long)); *ptr1 = var; *ptr0 = llvar; return 0; } /* * */ __device__ __host__ int toVars(char* buffer, unsigned* var, unsigned long long* llvar) { unsigned long long* ptr0 = reinterpret_cast<unsigned long long*>(buffer); unsigned* ptr1 = reinterpret_cast<unsigned*>(buffer+sizeof(unsigned long long)); //printf("Addresses: %p %p\n", ptr0, ptr1); *var = *ptr1; *llvar = *ptr0; return 0; } /* * */ __global__ void kernel(char* buffer, unsigned size) { unsigned id = threadIdx.x + blockDim.x*blockIdx.x; unsigned var = 0; unsigned long long llvar = 0; if(id>0) return; for(unsigned k=0; k<size; ++k) printf("%u ", buffer[k]); printf("\n"); int err = toVars(buffer, &var, &llvar); if(err) printf("Error %d.\n", err); else { printf("CUDA: %u %llu\n", var, llvar); } } /* * */ int main() { unsigned var = 42; unsigned long long llvar = 123456789123456789; const size_t BUFFER_COUNT = sizeof(unsigned) + sizeof(unsigned long long); char* buffer = new char[BUFFER_COUNT]; char* dbuffer = NULL; int err = 0; printf("Vars: %u %llu\n", var, llvar); // --- CPU --- err = toBuffer(buffer, var, llvar); if(err) return err; var = llvar = 0; err = toVars(buffer, &var, &llvar); if(err) return err; printf("CPU: toVars(): %u %llu\n", var, llvar); // --- CUDA --- HANDLE_ERROR( cudaSetDevice(0) ); HANDLE_ERROR( cudaMalloc((void**)(&dbuffer), BUFFER_COUNT*sizeof(char)) ); HANDLE_ERROR( cudaMemcpy(dbuffer, buffer, BUFFER_COUNT*sizeof(char), cudaMemcpyHostToDevice) ); kernel<<<1,1>>>(dbuffer, BUFFER_COUNT); HANDLE_LAST("Kernel launch failed."); HANDLE_ERROR( cudaFree(dbuffer) ); HANDLE_ERROR( cudaDeviceReset() ); delete[] buffer; return 0; }
Labels:
cuda,
misaligned address,
serialization,
serializing arrays
Samstag, 18. Mai 2013
Planet Gravitation Map Simulator
Screenshot CUDA / OpenGL Demo of Gravitation Map Simulator |
This is just another fun demo for CUDA and OpenGL. It is a slightly modified version of the so called "random oscillating magnetic pendulum" (ROMP). A pixel represents a start position of one particle. This object becomes attracted by all the planets around due to their gravity. After a while the object is going to hit a planet. Now that corresponding pixel gets the color of that planet. You see an evolving map of "gravity" structures in realtime (more or less *cough*).
Download: (tested on Linux and Windows (VS2010), needs CUDA, OpenGL, GLUT, GLEW)
Download Source Code v1.1
Download Source Code v1.0
Positions and masses of the planets can be changed by the user as well as the scale of the map.
The simulation uses Euler or Runge-Kutta integration method for solving the
differential equation. It is also possible to use doubles instead of
floats for better precision.
The idea for this demo comes from a friend, he also implemented the algorithm in processing. I ported this to CUDA, so the stuff is entirely computed and rendered on the GPU. You need a Nvidia CUDA capable GPU for that.
The idea for this demo comes from a friend, he also implemented the algorithm in processing. I ported this to CUDA, so the stuff is entirely computed and rendered on the GPU. You need a Nvidia CUDA capable GPU for that.
Screenshot 2.1, different coloring |
Screenshot 2.2 |
Computation
Given a particle at position at a time t. This particle has a (positive) mass m. In our space there are n planets with their fixed positions and (positive) masses .The following equation represents the gravitational force of planet i acting on our particle. This force comes from Newton's law of universal gravitation:
This integration can be solved numerically, e.g. by Euler's method:
with and as the initial values. h is the size of every step and v represents the velocity of the particle.
Here you see some videos, which are showing the simulation more or less in realtime.
More:
Article by Ingo Berg, 2006, on magnetic pendulum with implementation (using Beeman's algorithm):
http://www.codeproject.com/Articles/16166/The-magnetic-pendulum-fractal
Mathematica implementation:
http://nylander.wordpress.com/2007/10/27/magnetic-pendulum-strange-attractor/
Some more stuff, videos:
http://magnetmfa.wikispaces.com/pendula?responseToken=05ae0f7708a5c4c989455051dc970f570
http://www.youtube.com/watch?v=duy8s8C7-Uc
http://www.youtube.com/watch?v=QXf95_EKS6E
Freitag, 26. April 2013
Raycasted Spheres and Point Sprites vs. Geometry Instancing (OpenGL 3.3)
Source code of sphere_shader examples (raycasted spheres and mesh-based spheres) written in OpenGL 3.3. Code also includes handy camera, shader classes and (GPU) timer functions based on glQueryCounter. Tested on Linux and Windows.
Dependencies: OpenGL, GLEW, and FREEGLUT and glm.
Download source code:
https://github.com/tdd11235813/spheres_shader
(Update: 2016/03/12 - refactoring of code framework)
Developing the QPTool I was interested in the performance of the different types of sphere visualizations.
- Spheres with Geometry Instancing (mesh-based)
- Sphere Impostors with hardware based Point Sprites (GL_POINT_SPRITE_ARB)
- Sphere Impostors with Geometry Shaders
- Sphere Impostors with common Shaders (Parameters via TBO)
- Sphere Impostors with common Shaders (Parameters duplicated in VBO)
Mesh-based Spheres
The first implementation uses mesh-based spheres by the help of geometry instancing [2].
In the initialization a sphere mesh is sent down to the GPU. By glDrawElementsInstanced(...) the object geometry gets cloned many times. A shader places these objects into the scene.
Usually this is a good improvement for visualizing a massive amount of same (complex) geometry.
In our case there are two disadvantages:
- Meshes are a visible inaccurate approximation of the spheres.
- Polygon data increases with the resolution of the spheres, slows down the application regardless of the screen resolution.
In this picture you see in the bottom part the artifacts by the polygon approximation of the spheres. The upper two parts show raycasted sphere impostors (screenshot from QPTool v0.9.7).
Sphere Impostors by Raycast-Shaders
These two pictures are from the sphere_shader examples. First picture
shows the mesh-based spheres and the second one the impostors.
If we want to use shaders to render the spheres in the fragment shader on our own, we need a billboard.
A billboard is a flat object, usually a quad (square), which faces the camera. [3]
This quad must be generated with texture coordinates before we can use it. A good explanation can be found here [4]. There are several ways to achieve this. It is possible to use hardware based point sprites, where for each vertex a billboard is created. In the vertex shader you just have to set the point size, which makes up the billboard size later. There are some issues with compatibility and correct visuals. If you take the particles demo from CUDA SDK, where this rendering method is utilized, you might notice wrong quad sizes, especially when the quads move to the borders of the screen. I tried to fix that, but there are still some glitches.
Another possibility uses geometry shader. Dummy vertices (one per sphere) are sent down to GPU and the geometry shader creates four vertices making the billboard for one sphere.
The last way would be sending four vertices per sphere with predefined texture coordinates down to the GPU. By this either a second data buffer is needed for the parameters OR all the parameters are duplicated (4x) in the vertex buffer object.
One disadvantage of the implemented sphere impostor shaders is, Early depth test is not possible, since z-buffer is computed in fragment shader.
Results
Setting: 800x600
Hardware: GPU Nvidia GTX 470 (Fermi), CPU Intel Quad Core i7 @3.07GHz, 12GB RAM
OS: Windows 7 64bit
Number of spheres: 100,000
Parameters per sphere: Position (4 floats), Color (4 floats), Radius (1 float)
Frames measured after warmup: 200
Benchmark Results of Rendering Methods for Spheres (in ms) | ||||||
---|---|---|---|---|---|---|
FOV = 60 | ||||||
Method | Avg1 | Avg2 | Min1 | Min2 | Max1 | Max2 |
Sphere Geometry Instanced | 121.523 | 0.013 | 121.173 | 0.006 | 122.134 | 0.023 |
Sphere Billboard Quads (TBO) | 7.080 | 0.022 | 6.938 | 0.017 | 7.201 | 0.029 |
Sphere Billboard Quads (VBO) | 1.879 | 0.002 | 1.874 | 0.001 | 1.886 | 0.003 |
Sphere Impostor Geometry Shader | 1.915 | 0.001 | 1.900 | 0.001 | 1.933 | 0.002 |
Sphere Point Sprites, with Glitches :( | 1.541 | 0.001 | 1.501 | 0.001 | 1.619 | 0.002 |
FOV = 20 | ||||||
Sphere Geometry Instanced | 121.606 | 0.015 | 121.081 | 0.003 | 122.083 | 0.027 |
Sphere Billboard Quads (TBO) | 8.320 | 0.023 | 8.291 | 0.019 | 8.359 | 0.031 |
Sphere Billboard Quads (VBO) | 8.230 | 0.001 | 8.227 | 0.001 | 8.234 | 0.001 |
Sphere Impostor Geometry Shader | 8.229 | 0.001 | 8.224 | 0.001 | 8.243 | 0.001 |
Sphere Point Sprites, with Glitches :( | 7.756 | 0.001 | 7.752 | 0.001 | 7.763 | 0.001 |
FOV: Field of view. The lower the value, the more sphere-pixels have to be drawn. It is like zoom. | ||||||
***1: Value for whole frame in ms. | ||||||
***2: Value for binding and shader config in ms. |
Sphere Impostor Geometry Shader: Takes 1 dummy vertex, creates 4 vertices for billboard on the fly.
Sphere Billboard Quads: Takes 4 vertices with preset texture coordinates for billboard. Uses either texture buffer object (TBO) for sphere parameters or parameters which are duplicated (4x) as vertex attributes in the vertex buffer object (VBO).
Sphere Geometry Instanced: Polygon representation of sphere. Using geometry instancing.
Sphere Point Sprites. Hardwarebased Billboard generation (point sprites). Alas, there are glitches and incompatibilities, so I do not recommend to use this.
My current implementation uses the geometry shader method, because it has no glitches so far and it is fast. Nevertheless I would recommend to use predefined billboards with duplicated data, since you will not find geometry shader support "everywhere".
On Linux with a Kepler GPU I obtained following interesting results:
Setting: 800x600
Hardware: GPU Nvidia GTX 670 (Kepler), CPU Intel Quad Core i7 @3.4GHz, 8GB RAM
OS: Linux Kubuntu 12.04
Number of spheres: 100,000
Parameters per sphere: Position (4 floats), Color (4 floats), Radius (1 float)
Frames measured after warmup: 200
Please leave a comment, if you encounter bugs or know more or if you have other ideas.
On Linux with a Kepler GPU I obtained following interesting results:
Setting: 800x600
Hardware: GPU Nvidia GTX 670 (Kepler), CPU Intel Quad Core i7 @3.4GHz, 8GB RAM
OS: Linux Kubuntu 12.04
Number of spheres: 100,000
Parameters per sphere: Position (4 floats), Color (4 floats), Radius (1 float)
Frames measured after warmup: 200
Benchmark Results of Rendering Methods for Spheres (in ms) | ||||||
---|---|---|---|---|---|---|
FOV = 60 | ||||||
Method | Avg1 | Avg2 | Min1 | Min2 | Max1 | Max2 |
Sphere Geometry Instanced | 50.943 | 0.003 | 50.370 | 0.001 | 53.117 | 0.013 |
Sphere Billboard Quads (TBO) | 1.087 | 0.003 | 1.069 | 0.001 | 1.159 | 0.010 |
Sphere Billboard Quads (VBO) | 1.061 | 0.001 | 1.059 | 0.001 | 1.064 | 0.002 |
Sphere Impostor Geometry Shader | 1.066 | 0.001 | 1.063 | 0.001 | 1.069 | 0.003 |
Sphere Point Sprites, with Glitches :( | 0.897 | 0.001 | 0.895 | 0.001 | 0.902 | 0.003 |
FOV = 20 | ||||||
Sphere Geometry Instanced | 50.798 | 0.004 | 50.356 | 0.001 | 53.487 | 0.015 |
Sphere Billboard Quads (TBO) | 6.191 | 0.001 | 6.137 | 0.001 | 6.747 | 0.008 |
Sphere Billboard Quads (VBO) | 6.133 | 0.001 | 6.130 | 0.001 | 6.137 | 0.003 |
Sphere Impostor Geometry Shader | 6.121 | 0.001 | 6.116 | 0.001 | 6.127 | 0.002 |
Sphere Point Sprites, with Glitches :( | 5.442 | 0.001 | 5.440 | 0.001 | 5.446 | 0.002 |
FOV: Field of view. The lower the value, the more sphere-pixels have to be drawn. It is like zoom. | ||||||
***1: Value for whole frame in ms. | ||||||
***2: Value for binding and shader config in ms. |
Please leave a comment, if you encounter bugs or know more or if you have other ideas.
[1] -
https://web.archive.org/web/20150215085719/http://www.arcsynthesis.org/gltut/illumination/tutorial%2013.html
[2] - http://wiki.delphigl.com/index.php/shader_Instancing
[3] - http://nehe.gamedev.net/article/billboarding_how_to/18011/
[4] - http://www.sunsetlakesoftware.com/2011/05/08/enhancing-molecules-using-opengl-es-20
Labels:
Billboard,
Geometry Instancing,
glQueryCounter,
GLSL Geometry Shader,
Many Spheres,
OpenGL Benchmark,
Point Sprites,
Raycasting Shader,
Sphere Impostor,
Texture Buffer Object
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