Date: Thu, 6 Aug 2015 20:24:16 -0700 From: Doug Hardie <bc979@lafn.org> To: Peter Jeremy <peter@rulingia.com>, FreeBSD Stable ML <stable@freebsd.org> Subject: Re: Swap Usage Message-ID: <64F9A45B-DB9D-4827-B5E8-0E15E395157A@lafn.org> In-Reply-To: <BCB80170-3E1E-4861-B159-CD52472FB475@lafn.org> References: <BCA67F7E-676A-4226-83A0-84229948895E@lafn.org> <20150730064444.GA88137@server.rulingia.com> <10F94D23-E58C-466E-ADCA-5E6670054BD7@lafn.org> <BCB80170-3E1E-4861-B159-CD52472FB475@lafn.org>
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Some more testing indicates that the problem is most likely in close, not mmap. I modified the program to the following:
zool# more test.c
#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/mman.h>
int main (int argc, char *argv[])
{
int rc, pid, fd;
char *cp;
char cmd[1024];
pid = getpid ();
sprintf (cmd, "procstat -v %d | grep df", pid);
fflush (stdout);
rc = system (cmd);
fflush (stdout);
printf ("----------------------------------\n");
fd = open ("./test.c", O_RDWR);
fflush (stdout);
rc = system (cmd);
fflush (stdout);
printf ("----------------------------------\n");
close (fd);
fflush (stdout);
rc = system (cmd);
fflush (stdout);
}
The output is:
zool# ./test
85860 0x8049000 0x804a000 rw- 1 0 1 0 CN-- df
85860 0x2805f000 0x28069000 rw- 10 0 1 0 C--- df
85860 0x28186000 0x281ad000 rw- 13 0 1 0 CN-- df
85860 0xbfbdf000 0xbfbff000 rwx 3 0 1 0 C--D df
----------------------------------
85860 0x8049000 0x804a000 rw- 1 0 1 0 CN-- df
85860 0x804a000 0x8400000 rw- 1 0 1 0 CN-- df
85860 0x2805f000 0x28069000 rw- 10 0 1 0 CN-- df
85860 0x28186000 0x281ad000 rw- 14 0 1 0 CN-- df
85860 0x28400000 0x28800000 rw- 6 0 1 0 CN-- df
85860 0xbfbdf000 0xbfbff000 rwx 3 0 1 0 C--D df
----------------------------------
85860 0x8049000 0x804a000 rw- 1 0 1 0 CN-- df
85860 0x804a000 0x8400000 rw- 1 0 1 0 CN-- df
85860 0x2805f000 0x28069000 rw- 10 0 1 0 CN-- df
85860 0x28186000 0x281ad000 rw- 14 0 1 0 CN-- df
85860 0x28400000 0x28800000 rw- 6 0 1 0 CN-- df
85860 0xbfbdf000 0xbfbff000 rwx 3 0 1 0 C--D df
Open creates 2 memory allocations, one in low memory and one in high. Close does not remove them. Somewhere in the source I found a note that said that close on files didn’t require any action. However, those two memory allocations do need to get freed.
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