[dm-devel] [PATCH 2/3] set pthread stack size to at least PTHREAD_STACK_MIN

[Joe Thornber]

2009/3/16 Benjamin Marzinski <bmarzins at redhat.com>:
> I definitely see a problem if we use the default stacksize on ia64
> machines.  In RHEL5 at least, it's 10Mb per thread.  With one waiter
> thread per multipath device, you get a gigabyte of memory wasted on
> machines with over a hundred multipath devices.

You need to check whether this is 1G of physical memory, or just a 1G
chunk out of the address space.

Some threads need to have their stack reserved and locked into memory
before calls into the kernel.  This avoids deadlocks where the stack
gets paged out, but he vm can't page it back in until the thread
completes ...

It sounds like you have many more threads running these days than when
I last looked at LVM, it's not clear to me how many of these are ones
that need their stacks mem-locking.  Do you have an idea ?

If they don't need mem-locking then as long as you're not forcing the
stack to be physically allocated I wouldn't worry too much about
consuming address space.

Hope that ramble made sense,

- Joe