Created
July 7, 2019 10:52
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4 KiB tmpfs read
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| use std::sync::atomic::{AtomicUsize, Ordering}; | |
| // Usage: Make a 4 KiB file located at /mnt/tmpfstest/test.bin and run the | |
| // tool with `cargo run --release` | |
| /// Runs multiple threads at a time incrementally displaying the syscall | |
| /// throughput of 4-KiB random reads to a `tmpfs` hosted mountpoint | |
| fn benchmark_random_read_scaling() { | |
| for num_threads in 1..=256 { | |
| /// Lock to wait for all threads to spawn | |
| static THREAD_LOCKSTEPPER: AtomicUsize = AtomicUsize::new(0); | |
| /// CPU time spent (in cycles) | |
| static CYCLES: AtomicUsize = AtomicUsize::new(0); | |
| /// Number of file accesses to perform per thread | |
| const NUM_ACCESSES: usize = 4096; | |
| let mut threads = Vec::new(); | |
| // Reset lock and performance information | |
| THREAD_LOCKSTEPPER.store(0, Ordering::SeqCst); | |
| CYCLES.store(0, Ordering::SeqCst); | |
| for thr in 0..num_threads { | |
| threads.push(std::thread::spawn(move || { | |
| // Wait for all threads to come online in a busy loop | |
| THREAD_LOCKSTEPPER.fetch_add(1, Ordering::SeqCst); | |
| while THREAD_LOCKSTEPPER | |
| .load(Ordering::SeqCst) != num_threads {} | |
| // Start a "timer" by storing the current CPU cycle count | |
| let start = unsafe { core::arch::x86_64::_rdtsc() }; | |
| for _ in 0..NUM_ACCESSES { | |
| assert!(std::fs::read("/mnt/tmpfstest/test.bin") | |
| .unwrap().len() == 4096); | |
| } | |
| // Compute number of CPU cycles for the operation | |
| let elapsed = unsafe { core::arch::x86_64::_rdtsc() - start }; | |
| CYCLES.fetch_add(elapsed as usize, Ordering::SeqCst); | |
| })); | |
| } | |
| // Wait for all threads to complete | |
| for thr in threads { | |
| thr.join().unwrap(); | |
| } | |
| // Get number of cycles spent by all of the workers | |
| let cycles = CYCLES.load(Ordering::SeqCst); | |
| print!("With {:4} active read threads: {:10.1} cycles/file read\n", | |
| num_threads, cycles as f64 / (num_threads * NUM_ACCESSES) as f64); | |
| } | |
| } | |
| fn main() { | |
| print!("Warning: This is a benchmarking tool, make sure you're using \ | |
| --release!\n"); | |
| benchmark_random_read_scaling(); | |
| } | |
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