Messages in this thread | | | Date | Tue, 23 Oct 2001 15:19:45 -0500 | From | Dave McCracken <> | Subject | Issue with max_threads (and other resources) and highmem |
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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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