Re: [Linux-ia64] Re: [PATCH] Increase size of user stack

From: Matthew Wilcox <>
Date: 2003-05-13 00:44:17
On Mon, May 12, 2003 at 10:38:44AM -0400, Martin Hicks wrote:
> On Mon, May 05, 2003 at 11:25:33AM -0700, David Mosberger wrote:
> >   Martin> The current user stack size limit of 2GB is not big enough
> >   Martin> for large SMP or SSI clusters.  The following patch
> >   Martin> increases this size from 2GB to 512GB.  The new size is
> >   Martin> negotiable, but right now SGI has programs that require over
> >   Martin> 100GB of stack size on a 64 processor machine.  Setting the
> >   Martin> user stack size to 512GB seems like a reasonable thing to do
> >   Martin> for future growth.
> > 
> > Why not make it configurable via setrlimit() and be done with it once
> > and for all?
> (sorry for taking so long to respond about this)
> The user stack size is configurable through setrlimit().  The default 
> size of the user stack is 8MB and the max is ~0UL.  The problem is
> the addreses that are chosen for the stack (which grows down) and the
> register backing store (which grows up) are only 2GB apart.  My patch
> simply makes this space 512GB so that large stack are possible, without
> the stack smashing into the RBS.

Yes, but why not choose the addresses based on the current setting of
current->rlim[RLIMIT_STACK].rlim_max?  We could default that setting to
2GB (ie the same as what people are using now) and then set the RBS and
the user stack min(1TB, current->rlim[RLIMIT_STACK].rlim_max) apart.
Are there any disadvantages to doing this?

"It's not Hollywood.  War is real, war is primarily not about defeat or
victory, it is about death.  I've seen thousands and thousands of dead bodies.
Do you think I want to have an academic debate on this subject?" -- Robert Fisk
Received on Mon May 12 07:44:29 2003

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