tsb_alloc_hiwater = physical memory (bytes) / tsb_alloc_hiwater_factor
When the memory that is allocated to TSBs is equal to the value of tsb_alloc_hiwater, the TSB memory allocation algorithm attempts to reclaim TSB memory as pages are unmapped.
Exercise caution when using this factor to increase the value of tsb_alloc_hiwater. To prevent system hangs, the resulting high water value must be considerably lower than the value of swapfs_minfree and segspt_minfree.
1 to MAXINIT
Note that a factor of 1 makes all physical memory available for allocation to TSBs, which could cause the system to hang. A factor that is too high will not leave memory available for allocation to TSBs, decreasing system performance.
Change the value of this parameter if the system has many processes that attach to very large shared memory segments. Under most circumstances, tuning of this variable is not necessary.