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Message-ID: <20141204003653.GA5004@thin>
Date: Wed, 3 Dec 2014 16:36:54 -0800
From: Josh Triplett <josh@...htriplett.org>
To: Tim Bird <tim.bird@...ymobile.com>
Cc: Shuah Khan <shuahkh@....samsung.com>,
"linux-api@...r.kernel.org" <linux-api@...r.kernel.org>,
Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
Michael Ellerman <mpe@...erman.id.au>,
"linux-embedded@...r.kernel.org" <linux-embedded@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6] selftest: size: Add size test for Linux kernel
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@...ymobile.com>
v6 looks good to me.
Reviewed-by: Josh Triplett <josh@...htriplett.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
>
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