Date: Wed, 21 May 2008 13:46:20 -0500 From: Joshua Isom <jrisom@gmail.com> To: Bill Moran <wmoran@potentialtech.com> Cc: freebsd-questions@freebsd.org, Brad Penoff <penoff@cs.ubc.ca> Subject: Re: resident memory limit Message-ID: <b41a96fb2bc6a8090ea3ceefc930392e@gmail.com> In-Reply-To: <20080521133645.e327ffdf.wmoran@potentialtech.com> References: <b89c3c270805201320i36955dccv9c643543e1b3c291@mail.gmail.com> <20080520165437.36413c46.wmoran@potentialtech.com> <b89c3c270805201439nf8adbd4s954a80bb82c72ba@mail.gmail.com> <b89c3c270805210143l2019442am233aeeb8748fc776@mail.gmail.com> <20080521090919.e3e777ec.wmoran@potentialtech.com> <b89c3c270805211027o12fa20c8jb3fd6a635e764888@mail.gmail.com> <20080521133645.e327ffdf.wmoran@potentialtech.com>
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On May 21, 2008, at 12:36 PM, Bill Moran wrote: > In response to "Brad Penoff" <penoff@cs.ubc.ca>: >> On Wed, May 21, 2008 at 6:09 AM, Bill Moran >> <wmoran@potentialtech.com> wrote: >>> In response to "Brad Penoff" <penoff@cs.ubc.ca>: >>> >>>> On Tue, May 20, 2008 at 2:39 PM, Brad Penoff <penoff@cs.ubc.ca> >>>> wrote: >>>>> On Tue, May 20, 2008 at 1:54 PM, Bill Moran >>>>> <wmoran@potentialtech.com> wrote: >>>>>> In response to "Brad Penoff" <penoff@cs.ubc.ca>: >>>>>>> >>>>>>> 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 > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to > "freebsd-questions-unsubscribe@freebsd.org" > > 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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