[PATCH v6] selftest: size: Add size test for Linux kernel

[PATCH v6] selftest: size: Add size test for Linux kernel

[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@sonymobile.com>
---
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

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 45f145c..fa91aef 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -15,6 +15,7 @@ TARGETS += user
 TARGETS += sysctl
 TARGETS += firmware
 TARGETS += ftrace
+TARGETS += size
 
 TARGETS_HOTPLUG = cpu-hotplug
 TARGETS_HOTPLUG += memory-hotplug
diff --git a/tools/testing/selftests/size/.gitignore b/tools/testing/selftests/size/.gitignore
new file mode 100644
index 0000000..189b781
--- /dev/null
+++ b/tools/testing/selftests/size/.gitignore
@@ -0,0 +1 @@
+get_size
diff --git a/tools/testing/selftests/size/Makefile b/tools/testing/selftests/size/Makefile
new file mode 100644
index 0000000..04dc25e
--- /dev/null
+++ b/tools/testing/selftests/size/Makefile
@@ -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
diff --git a/tools/testing/selftests/size/get_size.c b/tools/testing/selftests/size/get_size.c
new file mode 100644
index 0000000..2d1af7c
--- /dev/null
+++ b/tools/testing/selftests/size/get_size.c
@@ -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);
+}
-- 
1.8.2.2

Re: [PATCH v6] selftest: size: Add size test for Linux kernel

[Josh Triplett]

On Wed, Dec 03, 2014 at 10:42:21AM -0800, Tim Bird wrote:
> 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-/MT0OVThwyLZJqsBc5GL+g@public.gmane.org>

v6 looks good to me.

Reviewed-by: Josh Triplett <josh-iaAMLnmF4UmaiuxdJuQwMA@public.gmane.org>

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

- Josh Triplett

> 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
> 
> diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
> index 45f145c..fa91aef 100644
> --- a/tools/testing/selftests/Makefile
> +++ b/tools/testing/selftests/Makefile
> @@ -15,6 +15,7 @@ TARGETS += user
>  TARGETS += sysctl
>  TARGETS += firmware
>  TARGETS += ftrace
> +TARGETS += size
>  
>  TARGETS_HOTPLUG = cpu-hotplug
>  TARGETS_HOTPLUG += memory-hotplug
> diff --git a/tools/testing/selftests/size/.gitignore b/tools/testing/selftests/size/.gitignore
> new file mode 100644
> index 0000000..189b781
> --- /dev/null
> +++ b/tools/testing/selftests/size/.gitignore
> @@ -0,0 +1 @@
> +get_size
> diff --git a/tools/testing/selftests/size/Makefile b/tools/testing/selftests/size/Makefile
> new file mode 100644
> index 0000000..04dc25e
> --- /dev/null
> +++ b/tools/testing/selftests/size/Makefile
> @@ -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
> diff --git a/tools/testing/selftests/size/get_size.c b/tools/testing/selftests/size/get_size.c
> new file mode 100644
> index 0000000..2d1af7c
> --- /dev/null
> +++ b/tools/testing/selftests/size/get_size.c
> @@ -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);
> +}
> -- 
> 1.8.2.2
> 

Re: [PATCH v6] selftest: size: Add size test for Linux kernel

[Shuah Khan]

On 12/03/2014 05:36 PM, Josh Triplett wrote:
> On Wed, Dec 03, 2014 at 10:42:21AM -0800, Tim Bird wrote:
>> 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-/MT0OVThwyLZJqsBc5GL+g@public.gmane.org>
> 
> v6 looks good to me.
> 
> Reviewed-by: Josh Triplett <josh-iaAMLnmF4UmaiuxdJuQwMA@public.gmane.org>
> 
> 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.

-- Shuah



-- 
Shuah Khan
Sr. Linux Kernel Developer
Samsung Research America (Silicon Valley)
shuahkh-JPH+aEBZ4P+UEJcrhfAQsw@public.gmane.org | (970) 217-8978

Re: [PATCH v6] selftest: size: Add size test for Linux kernel

[Shuah Khan]

On 12/03/2014 05:50 PM, Shuah Khan wrote:
> On 12/03/2014 05:36 PM, Josh Triplett wrote:
>> On Wed, Dec 03, 2014 at 10:42:21AM -0800, Tim Bird wrote:
>>> 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-/MT0OVThwyLZJqsBc5GL+g@public.gmane.org>
>>
>> v6 looks good to me.
>>
>> Reviewed-by: Josh Triplett <josh-iaAMLnmF4UmaiuxdJuQwMA@public.gmane.org>
>>
>> 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.
> 

Applied to kselftest fixes branch.

-- Shuah


-- 
Shuah Khan
Sr. Linux Kernel Developer
Samsung Open Source Group
Samsung Research America (Silicon Valley)
shuahkh-JPH+aEBZ4P+UEJcrhfAQsw@public.gmane.org | (970) 217-8978

RFC: kselftest size roadmap

[Tim Bird]

Here's an RFC on my roadmap for the kselftest size test going forward...

In the long term, I'd like to be able to use the test for bisecting
size regressions, and to allow any kernel developer to use this even if they
don't have hardware for a particular architecture.

What I'd like to add to this in the future:
 - cleaned up approach to cross-compilation
   - put CROSS_COMPILE handling outside sub-directory Makefiles
   - this should include support for KBUILD_OUTPUT
   - handle CFLAGS for user-space programs (as opposed to
     kernel CFLAGS), and in a unified way

 - ability to run on target or in emulator
   - will involve adding an "install phase", and 
   possibly a "collect results" phase.  These are needed
   throughout kselftest to do any host/target 
   testing.

 - add a size threshold parameter to allow the
  test to check for a regression
   - test needs to return failure code that git
    bisect can use (not sure about mechanism for this yet)
   - regression test might utilize a feature to save off a
   "baseline" size to measure against, for the ability 
   to indicate a regression as "current size > baseline + 20k"

Any feedback on this?

Thanks,
 -- Tim