On May 21, 2008, at 12:36 PM, Bill Moran wrote:
In response to "Brad Penoff" <[EMAIL PROTECTED]>:
On Wed, May 21, 2008 at 6:09 AM, Bill Moran
<[EMAIL PROTECTED]> wrote:
In response to "Brad Penoff" <[EMAIL PROTECTED]>:
On Tue, May 20, 2008 at 2:39 PM, Brad Penoff <[EMAIL PROTECTED]>
wrote:
On Tue, May 20, 2008 at 1:54 PM, Bill Moran
<[EMAIL PROTECTED]> wrote:
In response to "Brad Penoff" <[EMAIL PROTECTED]>:
I have an application that runs on Linux or Mac OS X but seems
to have
a problem when I run on FreeBSD (6.3 or 7). The issue is the
memory
footprint for the application (osubw_sctpclien below) is quite
large;
on Linux it can be as much as 950 MB in resident memory,
according to
top. However, on FreeBSD I start to get ENOMEM always around
the time
my resident memory size is about 200 MB.
I read a few posts and have seen people fixing their problems by
adjusting kern.maxdsiz in /boot/loader.conf and/or by adding a
swap
file. I've tried both and for my application, it still seems to
be
limited to 200 MB resident memory regardless of maxdsize and
swap file
setting. I wrote a toy application (malloctest below) that calls
malloc in a while(1) and breaks once it gets ENOMEM (doing
another
while(1) so it doesn't exit); this application's memory size in
top
always matches the kern.maxdsiz setting, however it has a very
low
resident memory number, according to top.
Have a look at /etc/login.conf and the associated man pages.
BTW, we've seen the exact behavior on FreeBSD 7 as well (6.3 was
reported here). We've tried on different hardware as well, and keep
getting haunted by this resident memory limit that we don't know how
to set.
Any idea why, in the data I originally reported, I can allocate
kern.maxdsiz + swap (see SIZE from top output) for malloc(1 MB) in a
while loop, yet the top value for RES is always really low?
How come, in contrast, my application starts to report ENOMEM when
SIZE is 203 MB and RES is 201 MB? This is why I titled the thread
asking about an unknown (to me ;-) limit for resident memory...
It's called memory overcommit. If the OS thinks it _might_ be able
to get you the memory, it will allow it. You only actually use the
memory when you start putting data in it (hence the difference
between
SIZE and RES) Add a statement to fill up the malloc()ed memory with
some sort of data in your loop, and you'll see different behaviour.
As to what's limiting your application, I'm not sure. What does the
output of 'ulimit -a' say?
Thanks again for your time.
With the default loader.conf, my "limit -a" output is:
Resource limits (current):
cputime infinity secs
filesize infinity kB
datasize 524288 kB
stacksize 65536 kB
coredumpsize infinity kB
memoryuse infinity kB
memorylocked infinity kB
maxprocesses 5547
openfiles 11095
sbsize infinity bytes
vmemoryuse infinity kB
My application starts getting ENOMEM when I have 201 MB of resident
memory.
When I change my loader.conf to match the 2 GB of physical memory
that I have:
kern.maxdsiz="2147483648"
kern.maxssiz="2147483648"
kern.dfldsiz="2147483648"
...and reboot, then my "limit -a" output is:
Resource limits (current):
cputime infinity secs
filesize infinity kB
datasize 2097152 kB
stacksize 2097152 kB
coredumpsize infinity kB
memoryuse infinity kB
memorylocked infinity kB
maxprocesses 5547
openfiles 11095
sbsize infinity bytes
vmemoryuse infinity kB
However, the application still seems to max out at 201 MB of resident
memory.
People suggest to fix my login.conf but the memory related fields are
set to unlimited... Any ideas where this 201 MB limit of resident
memory comes from?
That's pretty strange. If I had to guess, I would guess that there is
no
201M limit, but that you're hitting some other limit that just happens
to
predictably occur at 201M with that program.
I'm kind of grasping at straws here, so hopefully I won't lead you on a
wild goose chase, but I would look next at putting some debugging in
/etc/malloc.conf and seeing if you get any useful information from it
(see the malloc man page). From there, possibly a ktrace of the
process.
Hopefully you have source code for the program and can compile it with
debugging and run it under gdb.
--
Bill Moran
http://www.potentialtech.com
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Here's a question I haven't seen asked yet. How much memory is it
trying to allocate? If it can't get everything it's asking for it can
fail. Also, how is the application being started? There could be some
setting in the shell startup that's putting a limit. Is it a native
FreeBSD program or is it a linux executable running under simulation?
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