From b9ea871f8d180df58417cafa56a21f60190991eb Mon Sep 17 00:00:00 2001
From: Christoph Kirsch <ckirsch@gmail.com>
Date: Tue, 18 Jul 2023 10:00:38 +0200
Subject: [PATCH 1/3] Fixing tiny bug in profile output

---
 selfie.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/selfie.c b/selfie.c
index ebaae2db..260c6a02 100644
--- a/selfie.c
+++ b/selfie.c
@@ -10749,7 +10749,7 @@ void print_instruction_versus_exception_profile(uint64_t* parent_context) {
       ratio_format_integral_2(get_ic_all(parent_context), ic_count) + 1,
       ratio_format_fractional_2(get_ic_all(parent_context), ic_count));
     printf("%s:          %lu instructions per exception, handling %lu exceptions in total", selfie_name,
-      ec_count, ratio_format_integral_2(get_ic_all(parent_context), ec_count));
+      ratio_format_integral_2(get_ic_all(parent_context), ec_count), ec_count);
   }
   println();
 }

From 2f8503fb3b640de5d77b1025f1675b7c63a8f89c Mon Sep 17 00:00:00 2001
From: Christoph Kirsch <ckirsch@gmail.com>
Date: Tue, 18 Jul 2023 11:23:26 +0200
Subject: [PATCH 2/3] Introducing slowdown factor

---
 selfie.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/selfie.c b/selfie.c
index 260c6a02..c91f766b 100644
--- a/selfie.c
+++ b/selfie.c
@@ -10721,10 +10721,12 @@ void print_instruction_versus_exception_profile(uint64_t* parent_context) {
   uint64_t ec_count;
   uint64_t* context;
 
-  printf("%s:          %lu(%lu.%.2lu%%) executed instructions", selfie_name,
+  printf("%s:          %lu executed instructions [%lu.%.2lu%% share, factor %lu.%.2lu]\n", selfie_name,
     get_ic_all(parent_context),
     percentage_format_integral_2(get_total_number_of_instructions(), get_ic_all(parent_context)),
-    percentage_format_fractional_2(get_total_number_of_instructions(), get_ic_all(parent_context)));
+    percentage_format_fractional_2(get_total_number_of_instructions(), get_ic_all(parent_context)),
+    ratio_format_integral_2(get_total_number_of_instructions(), get_ic_all(parent_context)),
+    ratio_format_fractional_2(get_total_number_of_instructions(), get_ic_all(parent_context)));
 
   ic_count = 0;
   ec_count = 0;
@@ -10741,17 +10743,15 @@ void print_instruction_versus_exception_profile(uint64_t* parent_context) {
     context = get_next_context(context);
   }
 
-  if (ec_count > 0) {
+  if (ec_count > 0)
     // assert: get_ic_all(parent_context) > 0
-    printf(" [%lu.%.2lu%% overhead, factor %lu.%.2lu]\n",
+    printf("%s:          %lu exceptions handled by %lu instructions each [%lu.%.2lu%% overhead, factor %lu.%.2lu]\n", selfie_name,
+      ec_count,
+      ratio_format_integral_2(get_ic_all(parent_context), ec_count),
       percentage_format_integral_2(ic_count, get_ic_all(parent_context)),
       percentage_format_fractional_2(ic_count, get_ic_all(parent_context)),
       ratio_format_integral_2(get_ic_all(parent_context), ic_count) + 1,
       ratio_format_fractional_2(get_ic_all(parent_context), ic_count));
-    printf("%s:          %lu instructions per exception, handling %lu exceptions in total", selfie_name,
-      ratio_format_integral_2(get_ic_all(parent_context), ec_count), ec_count);
-  }
-  println();
 }
 
 void print_profile() {

From 84d1a668ea5885d6c72b4179282b697cfba46de8 Mon Sep 17 00:00:00 2001
From: Christoph Kirsch <ckirsch@gmail.com>
Date: Tue, 18 Jul 2023 16:51:50 +0200
Subject: [PATCH 3/3] Introducing context switching overhead measurement
 example

---
 Makefile            |  6 +++++-
 examples/overhead.c | 10 ++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)
 create mode 100644 examples/overhead.c

diff --git a/Makefile b/Makefile
index 213cc5c2..93f4edf3 100644
--- a/Makefile
+++ b/Makefile
@@ -52,7 +52,7 @@ selfie-gc-nomain.h: selfie-gc.h
 # Consider these targets as targets, not files
 .PHONY: self self-self self-self-check 64-to-32-bit \
 		whitespace quine escape debug replay \
-		emu emu-emu emu-emu-emu emu-vmm-emu os-emu os-vmm-emu \
+		emu emu-emu emu-emu-emu emu-vmm-emu os-emu os-vmm-emu overhead \
 		self-emu self-os-emu self-os-vmm-emu min mob \
 		gib gclib giblib gclibtest boehmgc cache \
 		sat brr bzz mon smt beat btor2 all
@@ -133,6 +133,10 @@ os-emu: selfie selfie.m
 os-vmm-emu: selfie selfie.m
 	./selfie -l selfie.m -m 3 -l selfie.m -y 2 -l selfie.m -y 1
 
+# Determine overhead of timer interrupts and context switching
+overhead: selfie selfie.m
+	./selfie -l selfie.m -m 2 -l selfie.m -c examples/overhead.c -y 1
+
 # Self-compile on emulator
 self-emu: selfie selfie.m selfie.s
 	./selfie -l selfie.m -m 3 -c selfie.c -o selfie-emu.m -s selfie-emu.s
diff --git a/examples/overhead.c b/examples/overhead.c
new file mode 100644
index 00000000..e35f1b8a
--- /dev/null
+++ b/examples/overhead.c
@@ -0,0 +1,10 @@
+// looping for measuring overhead of timer interrupts
+// as upper bound on overhead of context switching
+uint64_t main() {
+  uint64_t i;
+
+  i = 0;
+
+  while (i < 1000000000)
+    i = i + 1;
+}
\ No newline at end of file