IBM java: Turning on SMP seems more and more likely the key

Bill Fink billfink at
Wed May 29 10:54:28 EST 2002

On Tue May 28 2002, Graham Leggett wrote:

> James Gunning wrote:
> >          Have just verified that toggling SMP *on* is the critical
> > switch to get the IBM java to go.
> Had the same result here: SMP kernel + java = works.
> Trouble is the SMP kernel is noticably slower than the non SMP kernel on
> non SMP systems.

My best guess is that the bug is somewhere in /usr/src/linux/mm/slab.c
since that is the only part of the MM code that's dependent on CONFIG_SMP.
One difference I see is that the SMP code uses kmem_cache_alloc_batch
which is a real function, whereas the non-SMP code uses kmem_cache_alloc_one
which is a macro.  Also the SMP code writes something to the /proc file
system while the non-SMP code does not.  But I don't see anything obviously
wrong, although I'm certainly no expert in this area.


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