Merge pull request #1193 from jepler/sdcard-new-example

sdcardio: new example

Author: jepler

CircuitPython_sdcardio_sdioio/benchmark.py

@@ -0,0 +1,60 @@
+import time
+import os
+
+import mount_sd
+
+# First, just write the file 'hello.txt' to the card
+with open("/sd/hello.txt", "w") as f: print("hello world", file=f)
+
+print()
+print("SD card I/O benchmarks")
+
+# Test read and write speed in several scenarios:
+#  * 512 or 4096 bytes at a time
+#  * Writing 1 time or 16 times
+# First write the content to the SD card, then read it back, reporting the
+# time taken.
+for sz in 512, 4096:
+    b = bytearray(sz)
+    for i in range(sz): b[i] = 0xaa
+    for n in (1, 16):
+        with open("/sd/hello.bin", "wb") as f:
+            t0 = time.monotonic_ns()
+            for i in range(n):
+                f.write(b)
+            t1 = time.monotonic_ns()
+
+        dt = (t1-t0) / 1e9
+        print(f"write {len(b)} x {n} in {dt}s {n * len(b) / dt / 1000:.1f}Kb/s")
+
+        with open("/sd/hello.bin", "rb") as f:
+            t0 = time.monotonic_ns()
+            for i in range(n):
+                f.readinto(b)
+            t1 = time.monotonic_ns()
+
+        dt = (t1-t0) / 1e9
+
+        print(f"read  {len(b)} x {n} in {dt}s {n * len(b) / dt / 1000:.1f}Kb/s")
+        print()
+
+# Test "logging" speed and report the time to write each line.
+# Note that in this test the file is not closed or flushed after each
+# line, so in the event of power loss some lines would be lost.  However,
+# it allows much more frequent logging overall.
+#
+# If keeping data integrity is your highest concern, follow the logging
+# example, not this logging benchmark!
+print("logging test")
+with open("/sd/log.txt", "wt") as logfile:
+    t0 = time.monotonic_ns()
+    for i in range(10000):
+        t1 = time.monotonic_ns()
+        dt = (t1-t0) / 1e9
+        print(f"Line {i}, {dt:2f}s elapsed", file=logfile)
+t1 = time.monotonic_ns()
+dt = (t1-t0) / 1e9
+
+print(f"Logged 10000 lines in {dt} seconds, {dt*100:.0f}us/line")
+sz = os.stat('/sd/log.txt')[6]
+print(f"{sz} bytes written, {sz/dt/1000:.1f}Kb/s")