Re: Locating managed objects within ObjectAlloc (was Re: Garbage collection, core data, and tight loops)
Re: Locating managed objects within ObjectAlloc (was Re: Garbage collection, core data, and tight loops)
- Subject: Re: Locating managed objects within ObjectAlloc (was Re: Garbage collection, core data, and tight loops)
- From: Aaron Burghardt <email@hidden>
- Date: Sun, 4 Nov 2007 22:01:01 -0500
On Nov 4, 2007, at 5:36 PM, Ben Trumbull wrote:
On Nov 4, 2007, at 3:27 AM, email@hidden wrote:
No. The relationship is more complicated. For large blocks of
memory, malloc will return the allocation back to the kernel. For
small blocks, it will not, but instead coalesce the free space for
reuse later. The objects used in Core Data are almost exclusively
small. Amit
ptr = malloc(10 * 1024 * 1024);
Try again with something closer to the size of your managed
objects. Like 96-256 bytes.
Generally, I find RSIZE to reflect the high watermark of the
process, and use 'heap' to examine the currently free space within
it. Your mileage may vary. There's some pretty vociferous
disagreement over the "ideal" way to measure memory utilization
(available v.s. vm deallocated v.s. internal fragmentation, etc)
Yup, even 10 KB mallocs were small enough. For anyone that may be
following this thread, the following test looks different in Activity
Monitor (and and presumably ObjectAlloc). Once the VSIZE and RSIZE go
up, they stay at that level until the test quits:
#include <stdlib.h>
int main( int argc, char *argv[])
{
sleep(5);
char *ptr[1000];
int i;
while (1) {
for( i = 0; i < 1000; i++)
ptr[i] = malloc(10 * 1024);
sleep(10);
int j;
for( i = 0; i < 1000; i++) {
for( j = 0; j < (10 * 1024); j++)
*(ptr[i] + j) = 'x';
}
sleep(10);
for( i = 0; i < 1000; i++)
free(ptr[i]);
sleep(10);
}
}
Thanks again,
Aaron
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