Overview
Microbenchmarks to test the performance characteristics of the Emu Chick.
Building
Build for emu hardware/simulator:
mkdir build-hw && cd build-hw
cmake .. \
-DCMAKE_BUILD_TYPE=Release \
-DCMAKE_TOOLCHAIN_FILE=../cmake/emu-cxx-toolchain.cmake
make -j4
Build for testing on x86:
mkdir build-x86 && cd build-x86
cmake .. \
-DCMAKE_BUILD_TYPE=Debug
make -j4
Benchmarks
local_stream
Description
Allocates three arrays (A, B, C) with 2^log2_num_elements
on a single nodelet. Computes the sum of two vectors (C = A + B) with num_threads
threads, and reports the average memory bandwidth.
Usage
./local_stream mode log2_num_elements num_threads num_trials
Modes
- serial - Uses a serial for loop
- cilk_for - Uses a cilk_for loop
- serial_spawn - Uses a serial for loop to spawn a thread for each grain-sized chunk of the loop range
- recursive_spawn - Recursively spawns threads to divide up the loop range
- library - Uses
emu_local_for
fromemu_c_utils
global_stream
Allocates three arrays (A, B, C) with 2^log2_num_elements
using a chunked (malloc2D) array distributed across all the nodelets. Computes the sum of two vectors (C = A + B) with num_threads
threads, and reports the average memory bandwidth.
Usage
./global_stream mode log2_num_elements num_threads num_trials
Modes
- serial - Uses a serial for loop
- cilk_for - Uses a cilk_for loop
- serial_spawn - Uses a serial for loop to spawn a thread for each grain-sized chunk of the loop range
- recursive_spawn - Recursively spawns threads to divide up the loop range
- recursive_remote_spawn - Recursively spawns threads to divide up the loop range, using remote spawns where possible.
- serial_remote_spawn - Remote spawns a thread on each nodelet, then divides up work as in serial_spawn
- serial_remote_spawn_shallow - Like serial_remote_spawn, but all threads are remote spawned from nodelet 0.
- library - Uses
emu_chunked_array_apply
fromemu_c_utils
.
global_stream_1d
Allocates three arrays (A, B, C) with 2^log2_num_elements
using a striped array (malloc1dlong) distributed across all the nodelets. Computes the sum of two vectors (C = A + B) with num_threads
threads, and reports the average memory bandwidth.
Usage
./global_stream_1d mode log2_num_elements num_threads num_trials
Modes
- serial - Uses a serial for loop
- cilk_for - Uses a cilk_for loop
- serial_spawn - Uses a serial for loop to spawn a thread for each grain-sized chunk of the loop range
- library - Uses
emu_1d_array_apply
fromemu_c_utils
.
pointer_chase
The pointer chasing benchmark is defined as follows:
- Allocate a contiguous array of N elements. Each element consists of an 8-byte payload and an 8-byte pointer to the next element.
- Form a linked list by connecting the elements in random order.
- Each of P threads traverses N/P nodes in the list in parallel, summing up the payloads as it goes.
The randomization of elements in step 2 can be further controlled using the block_size
and sort_mode
parameters.
See the documentation for sort_mode
below.
Usage
./pointer_chase [OPTIONS]
--log2_num_elements Number of elements in the list
--num_threads Number of threads traversing the list
--block_size Number of elements to swap at a time
--spawn_mode How to spawn the threads
--sort_mode How to shuffle the array
--num_trials Number of times to run the benchmark
Spawn Modes
- serial_spawn - Uses a serial for loop to spawn a thread for each grain-sized chunk of the loop range
- serial_remote_spawn - Remote spawns a thread on each nodelet, then divides up work as in serial_spawn
Sort Modes
This parameter controls how the elements in the list are linked together.
In each example, the number refers to the index of the list element in the contiguous array.
Also --log2_num_elements=4
and --block_size=4
.
- ordered - Each element points to the next element in the array
0->1->2->3->4->5->6->7->8->9->10->11->12->13->14->15
- block_shuffle - The elements are grouped into blocks of size
block_size
, then the order of the blocks is randomized
4->5->6->7--->0->1->2->3--->12->13->14->15--->8->9->10->11
- intra_block_shuffle - The elements are grouped into blocks of size
block_size
, then the order of elements within each block is randomized
2->1->3->0--->4->5->7->6--->8->10->11->9--->14->15->13->12
- full_block_shuffle - The elements are grouped into blocks of size
block_size
. The order of elements within each block is randomized and the order of each block is randomized.
4->5->7->6--->2->1->3->0--->14->15->13->12--->8->10->11->9