updated setbrk_overhead

rust/setbrk_overhead.rs

@@ -0,0 +1,64 @@
+#![no_std]
+#![feature(asm)]
+
+use libtock::println;
+use libtock::result::TockResult;
+use libtock::memop;
+
+libtock_core::stack_size! {0x1800}
+
+const NUMBER_OF_SAMPLES: usize = 256;
+
+#[libtock::main]
+async fn main() -> TockResult<()> {
+    let drivers = libtock::retrieve_drivers()?;
+
+    drivers.console.create_console();
+
+    let perf = drivers.perf;
+
+
+    let base_brk: *const u8;
+    base_brk = memop::get_brk();
+
+    let mut times = [0 as usize; NUMBER_OF_SAMPLES];
+    let mut breaks = [0 as usize; NUMBER_OF_SAMPLES];
+
+    println!("Starting at break {:x}.", base_brk as usize);
+
+    // warmup
+    for i in 0..NUMBER_OF_SAMPLES {
+      let start: usize;
+      let end: usize;
+      let new_brk = base_brk as usize + (i * 8) % 4096*8;
+      start = perf.cycles().ok().unwrap();
+      let _valid = unsafe {memop::set_brk(new_brk as *const u8)};
+      end = perf.cycles().ok().unwrap();
+      times[i] = end - start;
+      breaks[i] = new_brk;
+    }
+
+    for i in 0..NUMBER_OF_SAMPLES {
+      let start: usize;
+      let end: usize;
+      let new_brk = base_brk as usize + (i * 8) % 4096*8;
+      start = perf.cycles().ok().unwrap();
+      let _valid = unsafe {memop::set_brk(new_brk as *const u8)};
+      end = perf.cycles().ok().unwrap();
+      times[i] = end - start;
+      breaks[i] = new_brk;
+    }
+
+    println!();
+    println!("### RESULTS ###");
+    println!("benchmark:, setbrk overhead");
+    println!("description:, Measures time time to change the break for the stack, this involves updating the MPU mapings");
+    println!("base_brk, {:x}", base_brk as usize);
+    println!("run, cycles, new_brk, new_brk_base_10");
+    for i in 0..NUMBER_OF_SAMPLES {
+        println!("{}, {}, {:x}, {}", i, times[i], breaks[i], breaks[i]);
+    }
+
+
+    Ok(())
+}