xcode 如何像活动监视器那样以编程方式检查 Mac 上的可用系统内存？
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How can I programmatically check free system memory on Mac like the Activity Monitor does?
提问by backspacer
On Mac OS X, I can see how much memory is free in Activity Monitor. How can I programmatically do this?
在 Mac OS X 上，我可以看到活动监视器中有多少可用内存。我怎样才能以编程方式做到这一点？
回答by Steven Kramer
This should do it. Google around for the exact meaning of the fields in the structures, but it should be pretty self-explanatory working from this code.
这应该做。谷歌搜索结构中字段的确切含义，但从这段代码开始工作应该是不言自明的。
#import <sys/sysctl.h>
#import <mach/host_info.h>
#import <mach/mach_host.h>
#import <mach/task_info.h>
#import <mach/task.h>
int mib[6];
mib[0] = CTL_HW;
mib[1] = HW_PAGESIZE;
int pagesize;
size_t length;
length = sizeof (pagesize);
if (sysctl (mib, 2, &pagesize, &length, NULL, 0) < 0)
{
fprintf (stderr, "getting page size");
}
mach_msg_type_number_t count = HOST_VM_INFO_COUNT;
vm_statistics_data_t vmstat;
if (host_statistics (mach_host_self (), HOST_VM_INFO, (host_info_t) &vmstat, &count) != KERN_SUCCESS)
{
fprintf (stderr, "Failed to get VM statistics.");
}
double total = vmstat.wire_count + vmstat.active_count + vmstat.inactive_count + vmstat.free_count;
double wired = vmstat.wire_count / total;
double active = vmstat.active_count / total;
double inactive = vmstat.inactive_count / total;
double free = vmstat.free_count / total;
task_basic_info_64_data_t info;
unsigned size = sizeof (info);
task_info (mach_task_self (), TASK_BASIC_INFO_64, (task_info_t) &info, &size);
double unit = 1024 * 1024;
memLabel.text = [NSString stringWithFormat: @"% 3.1f MB\n% 3.1f MB\n% 3.1f MB", vmstat.free_count * pagesize / unit, (vmstat.free_count + vmstat.inactive_count) * pagesize / unit, info.resident_size / unit];
回答by Ionic
Actually, that's only half true.
事实上，这只说对了一半。
free is not standard UNIX but a Linux-only command. You will neither find it on BSD, nor on OS X.
free 不是标准的 UNIX，而是一个仅限 Linux 的命令。您既不会在 BSD 上找到它，也不会在 OS X 上找到它。
For that matter, a better way to get memory information is through sysctl.
就此而言，获取内存信息的更好方法是通过 sysctl。
I.e. run
sysctl -a | grep -Ei "(hw|vm)\..*mem"
即运行
sysctl -a | grep -Ei "(hw|vm)\..*mem"
and you'll get the idea.
你会明白的。
To use this programmatically in C, refer to man sysctlbyname.
要在 C 中以编程方式使用它，请参阅man sysctlbyname。
Also, I don't see how GNOME System Monitorhelps on OS X.
另外，我看不到GNOME 系统监视器如何在 OS X 上提供帮助。
df is a good hint, though.
不过，df 是一个很好的提示。
If you just plan to use the shell to gather those data and opt for top, read man top. You can invoke top with -l 1 to get one sample only and limit the process table to, say, 20 processes with -n 20. Keep in mind that you won't get CPU values for procs using only sample, the reason is outlined in the man page.
如果您只是打算使用 shell 来收集这些数据并选择 top，请阅读man top。您可以使用 -l 1 调用 top 以仅获取一个样本，并使用 -n 20 将进程表限制为 20 个进程。请记住，您不会仅使用样本获取 procs 的 CPU 值，原因已概述在手册页中。
A simple example to get some information about memory out of top (complete lines only):
从顶部获取有关内存的一些信息的简单示例（仅限完整行）：
top -l1 -n 20 | grep -Ei "mem|vm"
top -l1 -n 20 | grep -Ei "mem|vm"
Hope that helps.
希望有帮助。
回答by tiktak
The usual commands to do that on UNIX are
在 UNIX 上执行此操作的常用命令是
- df -hfor hard drive usage
- freefor RAM and swapusage
- df -h硬盘使用
- 免费用于 RAM 和交换使用
You would then use/chain one or many of those to extract one of the information given: ack, sed, grep, head, cut, ...
然后，您将使用/链接其中一个或多个来提取给定的信息之一：ack、sed、grep、head、cut、...
Note: If you don't plan to "programmatically" check memory, I would advise you to rather use topto know which processes are using your CPU and RAM. Gnome System Monitoris one of its GUI equivalents.
注意：如果您不打算“以编程方式”检查内存，我建议您宁可使用top来了解哪些进程正在使用您的 CPU 和 RAM。 Gnome 系统监视器是其 GUI 等效项之一。
