Project 1: Weiqi Chen

README.md

@@ -1,11 +1,56 @@
+# Project 1 - Flocking Simulation
+
 **University of Pennsylvania, CIS 565: GPU Programming and Architecture,
 Project 1 - Flocking**
 
-* (TODO) YOUR NAME HERE
-  * (TODO) [LinkedIn](), [personal website](), [twitter](), etc.
-* Tested on: (TODO) Windows 22, i7-2222 @ 2.22GHz 22GB, GTX 222 222MB (Moore 2222 Lab)
+* Weiqi Chen
+  * [LinkedIn](https://www.linkedin.com/in/weiqi-ricky-chen-2b04b2ab/)
+* Tested on: Windows 10, i7-8750H @ 2.20GHz 2.21GHz, 16GB, GTX 1050 2GB
+
+## Screenshots
+| 5,000 Boids | 100,000 Boids |
+|--|--|
+|![Number of boids: 5k](images/5K.gif) | ![Number of boids: 60k](images/80k.gif) |
+
+## Performance Analysis
+### 1. Number of Boids
+The plot shows the FPS vs Boid Size for the 3 implementations.
+
+![](images/part1.png)
+
+* As the number of boids increases, performance decreases for all implementations.
+* Coherent grid has the best performance with large number of boids.
+* Visualization decreases performance.
+* The improvement from uniform grid to coherent uniform grid is more obvious as the number of boids increases.
+* The naive method is only good with a small number of boids.
+
+For each boid, naive method requires us to check every other boid, while uniform grid methods only need to check some/all of a boid's neighboring cells. Therefore computation
+time is decreased.
+
+### 2. Block Size
+
+![](images/part2.png)
+
+The plot below shows the FPS vs block size and visualization is turned off.
+* Performance is increased significantly when block size is increased from 16 to 32.
+* From block size 32 to 256, the performance is similar.
+Since the warp size is 32, a block size of less than 32 will lead to inactive threads in a warp. When block size is greater than 32, all threads will be used for parallel computation.
+
+### 3. Coherent Uniform Grid
+Coherent uniform grid has better performance than uniform grid. The more boids there are, the greater the difference. This is because:
+* We reorder `dev_pos` and `dev_vel` and boids in the same cell now occupy contiguous memory.
+
+* `dev_particleArrayIndices` in the global memory is accessed one time less, resulting in 1 level decrease of indirection.
+
+### 4. Cell Width
+Half cell width increases the performance due to decrease in computation. Assuming a neighborhood distance of 1:
+* For full cell width, 2, need to check a volume of 4<sup>3</sup> = 64
+* For half cell width, 1, need to check a volume of 3<sup>3</sup> = 27
 
-### (TODO: Your README)
+Using the coherent uniform grid implementation, we have:
 
-Include screenshots, analysis, etc. (Remember, this is public, so don't put
-anything here that you don't want to share with the world.)
+||Full Width (8 cells)| Half Width (27 cells)
+|--|--|--|
+|5k Boids|1431 FPS|1521 FPS|
+|15k Boids|1011 FPS | 1132FPS|
+|50k Boids|547 FPS |556 FPS|