Update drafts/2026-01-24-profiling-rust-written-network-program.md

drafts/2026-01-24-profiling-rust-written-network-program.md

@@ -1,4 +1,3 @@
-
 ## Testing enviornment setup
 Install tools:
 
@@ -191,3 +190,72 @@ Fix direction:
 move to smol::Executor + N threads (usually num_cpus)
 
 or run multiple block_on() workers (careful: avoid accept() duplication)
+
+
+## outcome
+
+### CPU hotspot
+testing commands: 
+
+```bash
+iperf3 -c 127.0.0.1 -p 9000 -t 30 -P 1
+
+sudo perf stat -p $(pidof oi) -e \
+  cycles,instructions,cache-misses,branches,branch-misses,context-switches,cpu-migrations \
+  -- sleep 30
+```
+
+perf report: 
+
+```text
+Performance counter stats for process id '207279':
+
+    98,571,874,480      cpu_atom/cycles/                                                        (0.10%)
+   134,732,064,800      cpu_core/cycles/                                                        (99.90%)
+    75,889,748,906      cpu_atom/instructions/           #    0.77  insn per cycle              (0.10%)
+   159,098,987,713      cpu_core/instructions/           #    1.18  insn per cycle              (99.90%)
+        30,443,258      cpu_atom/cache-misses/                                                  (0.10%)
+         3,155,528      cpu_core/cache-misses/                                                  (99.90%)
+    15,003,063,317      cpu_atom/branches/                                                      (0.10%)
+    31,479,765,962      cpu_core/branches/                                                      (99.90%)
+       149,091,165      cpu_atom/branch-misses/          #    0.99% of all branches             (0.10%)
+       195,562,861      cpu_core/branch-misses/          #    0.62% of all branches             (99.90%)
+             1,138      context-switches                                                      
+                37      cpu-migrations                                                        
+
+      33.004738330 seconds time elapsed
+```
+
+
+### FlameGraph
+testing commands:
+
+```bash
+sudo perf record -F 199 -g -p $(pidof oi) -- sleep 30
+sudo perf script | stackcollapse-perf.pl | flamegraph.pl > oi.svg
+```
+
+outcome:
+
+oi.svg
+
+commands:
+
+```bash
+sudo perf record -F 199 --call-graph dwarf,16384 -p $(pidof oi) -- sleep 30
+sudo perf script | stackcollapse-perf.pl | flamegraph.pl > oi_dwarf.svg
+```
+
+outcome:
+
+oi_dwarf.svg
+
+
+### syscall-cost check
+
+```bash
+sudo strace -ff -c -p $(pidof oi) -o /tmp/oi.strace
+# run 15–30s under load, then Ctrl+C
+tail -n +1 /tmp/oi.strace.*
+```
+