Date: Tue, 30 Jun 1998 10:05:08 -0700 (PDT) From: Thomas Dean <tomdean@ix.netcom.com> To: current@FreeBSD.ORG Subject: Physical Memory Allocation Message-ID: <199806301705.KAA00358@ix.netcom.com>
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This may not be a question for -current, but, it pertains to memory
allocation. I don't know if this happens on a non-current system.
I do not understand the shift of memory allocation between the various
categories used by top. Running a process which handles memory
properly should have little effect on memory allocation after it
exits. If I start netscape 3.01 and exit, there seems to be a
permanent shift of memory allocation from free to active and wired.
This does not happen with a process that allocates and then frees
memory.
I have attached information picked from top while these events
transpired and the code I used to allocate/free memory.
What is the definition of the memory allocation numbers in top?
I am running -current:
FreeBSD 3.0-CURRENT #0: Fri Jun 19 09:15:17 PDT 1998
root@celebris:/usr/src/sys/compile/CELEBRIS-SMP
Timecounter "i8254" frequency 1193182 Hz cost 2537 ns
CPU: Pentium/P54C (586-class CPU)
Origin = "GenuineIntel" Id = 0x525 Stepping=5
Features=0x3bf<FPU,VME,DE,PSE,TSC,MSR,MCE,CX8,APIC>
real memory = 100663296 (98304K bytes)
avail memory = 95272960 (93040K bytes)
FreeBSD/SMP: Multiprocessor motherboard
cpu0 (BSP): apic id: 0, version: 0x00030010, at 0xfee00000
cpu1 (AP): apic id: 1, version: 0x00030010, at 0xfee00000
io0 (APIC): apic id: 2, version: 0x000f0011, at 0xfec00000
============================================================
Use top to get memory use values.
After boot, running Emacs, reading mail, edit this text file.
Mem: 13M Active, 6200K Inact, 8500K Wired, 508K Cache, 3989K Buf, 65M Free
Start Netscape.
Mem: 17M Active, 7992K Inact, 9232K Wired, 808K Cache, 4621K Buf, 58M Free
Access a file with Netscape.
Mem: 19M Active, 8044K Inact, 9444K Wired, 760K Cache, 4813K Buf, 56M Free
Exit Netscape.
Mem: 15M Active, 8060K Inact, 10M Wired, 728K Cache, 5469K Buf, 59M Free
Start Netscape and access a file.
Mem: 20M Active, 8296K Inact, 10M Wired, 504K Cache, 5469K Buf, 54M Free
Exit Netscape.
Mem: 16M Active, 8296K Inact, 10M Wired, 504K Cache, 5469K Buf, 59M Free
Start Netscape and access a file.
Mem: 19M Active, 8300K Inact, 10M Wired, 504K Cache, 5469K Buf, 55M Free
Access the Alta Vista search page.
Mem: 19M Active, 8336K Inact, 10M Wired, 552K Cache, 5610K Buf, 55M Free
Exit Netscape.
Mem: 16M Active, 8380K Inact, 10M Wired, 552K Cache, 5588K Buf, 58M Free
Start memoryTest.c, allocate 2 each 10MB blocks and write to them.
Mem: 36M Active, 8364K Inact, 10M Wired, 540K Cache, 5759K Buf, 38M Free
After memoryTest.c exits.
Mem: 16M Active, 8360K Inact, 10M Wired, 536K Cache, 5759K Buf, 58M Free
Start memoryTest.c, allocate 2 each 10MB blocks and write to them.
Mem: 36M Active, 8372K Inact, 10M Wired, 536K Cache, 5759K Buf, 38M Free
After memoryTest.c exits.
Mem: 16M Active, 8360K Inact, 10M Wired, 536K Cache, 5759K Buf, 58M Free
Start memoryTest.c, allocate 2 each 10MB blocks and write to them.
Mem: 36M Active, 8388K Inact, 10M Wired, 536K Cache, 5760K Buf, 38M Free
After memoryTest.c exits.
Mem: 16M Active, 8376K Inact, 10M Wired, 536K Cache, 5760K Buf, 58M Free
============================================================
/*
memTest.c - Just use some memory.
calloc memory and write into it.
Syntax: memTest <max MB>
*/
#include <stdio.h>
#include <stdlib.h>
#define ONE_MB 1024*1024
main(int argc, char **argv) {
unsigned int testSize, jdx;
unsigned char *buf1, *buf2;
if (argc != 2) {
printf("Usage: %s <max MB>\n",argv[0]);
exit(0);
}
if (sscanf(argv[1], "%u", &testSize) != 1) {
printf("Error in argument: %s\n",argv[0]);
exit(0);
}
printf("allocatinging %uMB\n",testSize);
buf1 = (unsigned char *)calloc(1, testSize*ONE_MB);
if (!buf1) {
perror("calloc1");
exit(0);
}
buf2 = (unsigned char *)calloc(1, testSize*ONE_MB);
if (!buf2) {
perror("calloc2");
exit(0);
}
printf("Testing %uMB at %08x and %08x = %u\n",
testSize, buf1, buf2, (unsigned int)(buf2-buf1));
for (jdx=0; jdx<testSize*ONE_MB; jdx++) buf1[jdx] = 0xff;
for (jdx=0; jdx<testSize*ONE_MB; jdx++) buf2[jdx] = 0xff;
free(buf1);
free(buf2);
}
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