Re: Large Shared Memory

Bret Orsburn (borsburn@codonics.com)
Wed, 30 Jun 1999 18:25:39 -0400


Matti Aarnio wrote:
>
> On Wed, Jun 30, 1999 at 12:48:52PM -0400, Bret Orsburn wrote:
> > Worthies of the Linux Kernel List:
> >
> > I need to create a rather large region of shared memory -- on the order of 50MB.
> > More specifically, I need a contiguous region of memory that can be mapped into
> > multiple processes (serially, not simultaneously) on a uniprocessor system and
> > persist beyond any particular process.
> >
> > It appears that there is a limit on System V style shared memory segments of
> > about 4MB, so that method is out.
>
> (This is a FAQ with e.g. Oracle setup at Linux..)
>
> Size of the SysV SHM is runtime controlled by writing to:
> /proc/sys/kernel/shmmax
>
> # echo "55000000" > /proc/sys/kernel/shmmax
>
> Now your maximum SHM size is 55 million bytes (you get the idea ?)
>
> There are some limits at how high you can push that, but they
> are pretty high... At least 512 MB is possible at SysV SHM.

Wow! That's great news. I'll give it a try.

----

Bret Orsburn
borsburn@codonics.com

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