selftest: size: Add size test for Linux kernel

This test shows the amount of memory used by the system. Note that this is dependent on the user-space that is loaded when this program runs. Optimally, this program would be run as the init program itself.

The program is optimized for size itself, to avoid conflating its own execution with that of the system software.
The code is compiled statically, with no stdlibs. On my x86_64 system, this results in a statically linked binary of less than 5K.

Signed-off-by Tim Bird <tim.bird-/[email protected]>

Changes from v5:
- remove #ifdef in Makefile (doh!)
- use variables in build command
- use different num_to_str, with less conversions

Changes from v4:
- make most routines static
- replace strip with gcc -s
- remove explicit reference to _start
- change --static to -static
- remove explicit reference to LIBGCC
- fix test description for ok and not ok paths, for test 1

Changes from v3:
- add more human-readable output
- put libgcc reference into a variable in Makefile

Changes from v2:
- fix copyright string (again!)
- use __builtin_strlen instead of my own strlen
- replace main with _start

Changes from v1:
- add return values to print routines
- add .gitignore file
- use more correct Copyright string in get_size.c

 tools/testing/selftests/Makefile        |   1 +
 tools/testing/selftests/size/.gitignore |   1 +
 tools/testing/selftests/size/Makefile   |  12 ++++
 tools/testing/selftests/size/get_size.c | 100 ++++++++++++++++++++++++++++++++
 4 files changed, 114 insertions(+)
 create mode 100644 tools/testing/selftests/size/.gitignore
 create mode 100644 tools/testing/selftests/size/Makefile
 create mode 100644 tools/testing/selftests/size/get_size.c

tools/testing/selftests/Makefile +1 -0

index 45f145c..fa91aef 100644
@@ -15,6 +15,7 @@ TARGETS += user
 TARGETS += sysctl
 TARGETS += firmware
 TARGETS += ftrace
+TARGETS += size
 
 TARGETS_HOTPLUG = cpu-hotplug
 TARGETS_HOTPLUG += memory-hotplug

tools/testing/selftests/size/.gitignore new file +1 -0

new file mode 100644
index 0000000..189b781
@@ -0,0 +1 @@
+get_size

tools/testing/selftests/size/Makefile new file +12 -0

new file mode 100644
index 0000000..04dc25e
@@ -0,0 +1,12 @@
+CC = $(CROSS_COMPILE)gcc
+
+all: get_size
+
+get_size: get_size.c
+	$(CC) -static -ffreestanding -nostartfiles -s $< -o $@
+
+run_tests: all
+	./get_size
+
+clean:
+	$(RM) get_size

tools/testing/selftests/size/get_size.c new file +100 -0

new file mode 100644
index 0000000..2d1af7c
@@ -0,0 +1,100 @@
+/*
+ * Copyright 2014 Sony Mobile Communications Inc.
+ *
+ * Licensed under the terms of the GNU GPL License version 2
+ *
+ * Selftest for runtime system size
+ *
+ * Prints the amount of RAM that the currently running system is using.
+ *
+ * This program tries to be as small as possible itself, to
+ * avoid perturbing the system memory utilization with its
+ * own execution.  It also attempts to have as few dependencies
+ * on kernel features as possible.
+ *
+ * It should be statically linked, with startup libs avoided.
+ * It uses no library calls, and only the following 3 syscalls:
+ *   sysinfo(), write(), and _exit()
+ *
+ * For output, it avoids printf (which in some C libraries
+ * has large external dependencies) by  implementing it's own
+ * number output and print routines, and using __builtin_strlen()
+ */
+
+#include <sys/sysinfo.h>
+#include <unistd.h>
+
+#define STDOUT_FILENO 1
+
+static int print(const char *s)
+{
+	return write(STDOUT_FILENO, s, __builtin_strlen(s));
+}
+
+static inline char *num_to_str(unsigned long num, char *buf, int len)
+{
+	unsigned int digit;
+
+	/* put digits in buffer from back to front */
+	buf += len - 1;
+	*buf = 0;
+	do {
+		digit = num % 10;
+		*(--buf) = digit + '0';
+		num /= 10;
+	} while (num > 0);
+
+	return buf;
+}
+
+static int print_num(unsigned long num)
+{
+	char num_buf[30];
+
+	return print(num_to_str(num, num_buf, sizeof(num_buf)));
+}
+
+static int print_k_value(const char *s, unsigned long num, unsigned long units)
+{
+	unsigned long long temp;
+	int ccode;
+
+	print(s);
+
+	temp = num;
+	temp = (temp * units)/1024;
+	num = temp;
+	ccode = print_num(num);
+	print("\n");
+	return ccode;
+}
+
+/* this program has no main(), as startup libraries are not used */
+void _start(void)
+{
+	int ccode;
+	struct sysinfo info;
+	unsigned long used;
+
+	print("Testing system size.\n");
+	print("1..1\n");
+
+	ccode = sysinfo(&info);
+	if (ccode < 0) {
+		print("not ok 1 get runtime memory use\n");
+		print("# could not get sysinfo\n");
+		_exit(ccode);
+	}
+	/* ignore cache complexities for now */
+	used = info.totalram - info.freeram - info.bufferram;
+	print_k_value("ok 1 get runtime memory use # size = ", used,
+		info.mem_unit);
+
+	print("# System runtime memory report (units in Kilobytes):\n");
+	print_k_value("#   Total:  ", info.totalram, info.mem_unit);
+	print_k_value("#   Free:   ", info.freeram, info.mem_unit);
+	print_k_value("#   Buffer: ", info.bufferram, info.mem_unit);
+	print_k_value("#   In use: ", used, info.mem_unit);
+
+	_exit(0);
+}

Signature · 1 line

1.8.2.2

Quoted 10 lines · Tim Bird

This test shows the amount of memory used by the system. Note that this is dependent on the user-space that is loaded when this program runs. Optimally, this program would be run as the init program itself.

The program is optimized for size itself, to avoid conflating its own execution with that of the system software.
The code is compiled statically, with no stdlibs. On my x86_64 system, this results in a statically linked binary of less than 5K.

Quoted 1 line

Signed-off-by Tim Bird <tim.bird-/[email protected]>

v6 looks good to me.

Reviewed-by Josh Triplett <[email protected]>

Should this go through the tinification tree or the selftests tree?

Quoted 17 lines · Josh Triplett

Quoted 11 lines · Tim Bird

This test shows the amount of memory used by the system. Note that this is dependent on the user-space that is loaded when this program runs. Optimally, this program would be run as the init program itself.

The program is optimized for size itself, to avoid conflating its own execution with that of the system software.
The code is compiled statically, with no stdlibs. On my x86_64 system, this results in a statically linked binary of less than 5K.

Signed-off-by Tim Bird <tim.bird-/[email protected]>

v6 looks good to me.

Reviewed-by Josh Triplett <[email protected]>

Quoted 2 lines

Should this go through the tinification tree or the selftests tree?

Josh/Tim,

Thanks both. Yes v6 looks good. I will take this through kselftest tree. I will apply this to kselftes fixes.