rwatson at FreeBSD.org
Wed Nov 23 14:21:49 PST 2005
On Wed, 23 Nov 2005, Michael Conlen wrote:
> Sorry if this is the wrong place for this, but I haven't been getting
> answers elsewhere.
> I'm trying to tune the system to allow very large mmap()'s in a single
> process space, something on the order of 1.5 GB so I can pass very large
> values for -Xms and -Xmx to java. I know I had been able to do this on
> FreeBSD in the past but recent versions of either Java or FreeBSD aren't
> playing nicely. currently..
BTW, you may find it useful to use procfs to inspect the address space
layout of your process. You can d:
mount -t procfs proc /proc
dd if=map of=/dev/stdout bs=20k
This can help you look for fragmentation of process address space, among
Robert N M Watson
> I'm running
> FreeBSD host 6.0-RELEASE FreeBSD 6.0-RELEASE #0: Tue Nov 22 00:22:53 EST 2005
> root at host:/usr/obj/usr/src/sys/WWW i386
> I've also tried the following under 5.4-p1...
> I try
> rc = mmap(0, (891*1024*1024 + 0), 0, MAP_ANON | MAP_PRIVATE, -1, 0);
> and it works but If I try
> rc = mmap(0, (892*1024*1024 + 0), 0, MAP_ANON | MAP_PRIVATE, -1, 0);
> it fails returning ENOMEM.
> limit returns
> cputime unlimited
> filesize unlimited
> datasize 2096128 kbytes
> stacksize 1048576 kbytes
> coredumpsize unlimited
> memoryuse unlimited
> vmemoryuse unlimited
> descriptors 11095
> memorylocked unlimited
> maxproc 5547
> sbsize unlimited
> If the program isn't doing anything else but that is there any reason I'm
> getting limited in the amount of memory I can mmap() at about 892 MB? Ideally
> I'd like to be able to mmap most of the 2 GB available to user procs.
> Oh, yes, there's plenty of free memory and swap.
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