Question

it is possible on the iPhone to get the memory consumption for a specific program? For example, I want to know how many memory my program is used without using the instrument tool.

Thanks in advance.
Alex

Answer 1

I’d highly recommend using the Memory Monitor instrument to track a particular application’s memory usage.

You can get system-wide memory usage statistics via a function like the following:

#import <mach/mach.h>
#import <mach/mach_host.h>

static void print_free_memory () {
    mach_port_t host_port;
    mach_msg_type_number_t host_size;
    vm_size_t pagesize;

    host_port = mach_host_self();
    host_size = sizeof(vm_statistics_data_t) / sizeof(integer_t);
    host_page_size(host_port, &pagesize);        

    vm_statistics_data_t vm_stat;

    if (host_statistics(host_port, HOST_VM_INFO, (host_info_t)&vm_stat, &host_size) != KERN_SUCCESS)
        NSLog(@"Failed to fetch vm statistics");

    /* Stats in bytes */ 
    natural_t mem_used = (vm_stat.active_count +
                          vm_stat.inactive_count +
                          vm_stat.wire_count) * pagesize;
    natural_t mem_free = vm_stat.free_count * pagesize;
    natural_t mem_total = mem_used + mem_free;
    NSLog(@"used: %u free: %u total: %u", mem_used, mem_free, mem_total);
}

This code is copied from Landon Fuller’s post on the topic. Noel Llopis also has a nice writeup on investigating memory usage from within an application. Unfortunately, it doesn’t look like it’s easy to know an application’s memory usage from within that application itself.