chore: add sample freq modifier

Author: not-matthias

src/run/runner/wall_time/perf/mod.rs

@@ -155,10 +155,14 @@ impl PerfRunner {
             }
         };
 
+        let sample_freq = std::env::var("CODSPEED_PERF_SAMPLE_FREQ")
+            .ok()
+            .and_then(|freq| freq.parse::<u32>().ok())
+            .unwrap_or(999);
         cmd.args([
             "-c",
             &format!(
-                "sudo perf record {quiet_flag} --user-callchains --freq=999 --switch-output --control=fifo:{},{} --delay=-1 -g --call-graph={cg_mode} --output={} -- {bench_cmd}",
+                "sudo perf record {quiet_flag} --user-callchains --freq={sample_freq} --switch-output --control=fifo:{},{} --delay=-1 -g --call-graph={cg_mode} --output={} -- {bench_cmd}",
                 perf_fifo.ctl_fifo_path.to_string_lossy(),
                 perf_fifo.ack_fifo_path.to_string_lossy(),
                 perf_file.path().to_string_lossy(),