I recently had pointed out to me that the default value for max_threads (ie
the max number of tasks per system) doesn't work right on machines with
lots of memory.
A quick examination of fork_init() shows that max_threads is supposed to be
limited so its stack/task_struct takes no more than half of physical
memory. This calculation ignores the fact that task_structs must be
allocated from the normal pool and not the highmem pool, which is a clear
bug. On a machine with enough physical memory it's possible for all of
normal memory to be allocated to task_structs, which tends to make the
machine die.
fork_init() gets its knowledge of physical memory passed in from
start_kernel(), which sets it from mum_physpages. This parameter is also
passed to several other init functions.
My question boils down to this... Should we change start_kernel() to limit
the physical memory size it passes to the init functions to not include
high memory, or should we only do it for fork_init()? What is the best way
to do calculate this number? I don't see any simple way in
architecture-independent code to get the size of high memory vs normal
memory.
What's the best approach here?
Thanks,
Dave McCracken
======================================================================
Dave McCracken IBM Linux Base Kernel Team 1-512-838-3059
dmccr@us.ibm.com T/L 678-3059
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This archive was generated by hypermail 2b29 : Tue Oct 23 2001 - 21:00:40 EST