Memory usage of a running script. 2 methods, 2 different results

Hello all, I've been working on a small extension that can tell me the memory usage of a script in run-time. I've discovered two methods of doing so (when PHP is compiled with debugging and memory limit). One is by reading the AG(allocated_memory) and/or AG(allocated_memory_peak) global var, the other is a construction like this (partially taken from the pdf extension as i recall):

        int allocated_memory = 0;
        int allocated_pmemory = 0;
        int allocated_memory_total = 0;
        zend_mem_header *zmh, *zpmh;

        zmh = AG(head);
        while(zmh != NULL) {
                allocated_memory += zmh->size;
                zmh = zmh->pNext;
        }
        zpmh = AG(phead);
        while(zpmh != NULL) {
                allocated_pmemory += zpmh->size;
                zpmh = zpmh->pNext;
        }
        allocated_memory_total = allocated_memory + allocated_pmemory;

Strange thing is, i get different results with these two methods. Running a test script that outputs results of both methods gives me the following: 1st method: Current memory usage: 545331 Peak memory usage: 545331 2nd method: Memory: regular(68423) persistent(0) total(68423) Now i wonder which method is right, and where the difference in results comes from. Or am i doing this all wrong? Can someone please shed some light on this? System is Linux-2.4.18, Apache_1.3.24, php-4.2.1, php built as an Apache module with debugging and memory limit. Thanks in advance. With kind regards, Hans Rakers Parse BV, the Netherlands