Add plots to context switch benchmarks.

app/context_switch/fiber_continue_arm32.s

@@ -11,7 +11,7 @@ __fiber_continue:
         * r0 = continuation that returned control back to the caller (null if fallthrough)
         *
         * Variables
-        * r4 = temporary for the old stack pointer */
+        * r1 = temporary for the old stack pointer */
 
         /* ========== Save State ========== */
         /* store programm counter for later return */
@@ -22,7 +22,7 @@ __fiber_continue:
 
         /* Perform change to new stack */
         /* Keep old stack as result from this function. */
-        mov r4, sp
+        mov r1, sp
         /* Switch to new stack pointer. */
         mov sp, r0
 
@@ -34,5 +34,5 @@ __fiber_continue:
 
         /* Just return back from the call. */
         /* This is the end of a fiber, so we have no continuation. */
-        mov r0, r4
+        mov r0, r1
         pop {pc}

app/context_switch/fiber_continue_x86_64.s

@@ -11,9 +11,6 @@ __fiber_continue:
         # Return
         # rax = continuation that returned control back to the caller (null if fallthrough)
 
-        # Variables
-        # r12 = temporary for the old stack pointer
-
         ############### Save State ###############
         # Make space for all register state we will store.
         leaq -0x38(%rsp), %rsp
@@ -33,7 +30,7 @@ __fiber_continue:
 
         # Perform change to new stack.
         # Keep old stack as result from this function
-        movq %rsp, %r12
+        movq %rsp, %rax
         # switch to new stack pointer
         movq %rdi, %rsp
 
@@ -55,5 +52,5 @@ __fiber_continue:
         ############ Restore State  ############
 
         # Return the context we came from as a continuation.
-        movq %r12, %rax
+        # Result is already in rax.
         ret

app/context_switch/measurements/plot.py

 import numpy as np
 from matplotlib import pyplot as plt
+from matplotlib.patches import Patch
 
 labels = ['loop overhead',
           'function call',
           'stack switching',
-          'setjmp + stack switching',
-          'fcontext switch, return',
-          'fcontext create, switch, return',
-          'pseudo callcc',
-          'custom'
+          'setjmp and stack switching',
+          'minimal fcontext overhead',
+          'minimum callcc overhead',
+          'custom assembly'
           ]
 
 call_color = (0.3, 0.1, 0.4, 0.6)
@@ -22,7 +22,6 @@ colors = [
     setjmp_color,
     fcontext_color,
     fcontext_color,
-    fcontext_color,
     custom_color
 ]
 
@@ -31,29 +30,57 @@ dataX86 = np.array([
     2.79,
     5.60,
     14.93,
-    9.51,
     11.00,
     18.66,
     7.86,
 ])
-dataARM32 = np.array([  # TODO: Run and fill in data...damn that laptop crash
+dataARM32 = np.array([
     1.26,
     4.97,
     11.25,
     54.50,
-    51.93,
     57.45,
     101.29,
     23.74,
 ])
-data = dataARM32
 
-assert (len(labels) == len(data), "Must fill in all data!")
-xAxis = np.array(range(0, len(labels)))
 
-plt.bar(xAxis, data, color=colors)
-plt.xticks(xAxis, labels, rotation=90)
-plt.ylabel('runtime in ns')
-plt.subplots_adjust(bottom=0.5, top=0.98)
+def plot_data(data, name):
+    plt.clf()
+
+    # Make sure pgf plots have correct fonts
+    pgf_with_rc_fonts = {
+        "font.family": "serif",
+        "font.serif": [""],
+        "font.sans-serif": [""],
+    }
+    plt.rcParams.update(pgf_with_rc_fonts)
+
+    xAxis = np.array(range(0, len(labels)))
+
+    plt.bar(xAxis, data, color=colors)
+    plt.xticks(xAxis, labels, rotation=90)
+    plt.ylabel('runtime in ns')
+    plt.subplots_adjust(bottom=0.5, top=0.98)
+
+    custom_lines = [Patch(facecolor=call_color, edgecolor='k'),
+                    Patch(facecolor=setjmp_color, edgecolor='k'),
+                    Patch(facecolor=fcontext_color, edgecolor='k'),
+                    Patch(facecolor=custom_color, edgecolor='k')]
+    custom_labels = ['baseline',
+                     'setjmp',
+                     'fcontext',
+                     'custom']
+    plt.legend(custom_lines, custom_labels)
+
+    fig = plt.gcf()
+    fig.set_size_inches(5, 5)
+    fig.set_dpi(300)
+    # bounds = Bbox.from_bounds(-0.1, -0.1, 4.75, 4.6)
+
+    fig.savefig(name + '.pgf')
+    fig.savefig(name + '.png')
+
 
-plt.show()
+plot_data(dataX86, "plots/context_switch_x86_64")
+plot_data(dataARM32, "plots/context_switch_arm32")

app/context_switch/measurements/readme.md

+# Context Switch Measurements
+
+The goal of these 'quick and dirty' measurements is to get a feeling for the
+expected minimum runtime of different operations involved in cotext switching/
+stackfull coroutines.
+
+We compare a jump_buf + stack pointer manipulation method, boost.context (represented
+the c wrapper around their assembly to avoid importing whole boost), a custom 
+fiber call written by us in assembly and finally some baseline for method call costs.
+
+We plot the results for both an x86_64 and arm32 system to decide what implementation
+we choose for pls, as this operation will be performed for every single task creation.