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Avoiding buffer manager thrashing
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Example of -threads
option
The results of the -threads option look like the following:
Options string for Main cache: "-threads -file_suffix threads-iqmon -append
-interval 10"
Threads
2000-01-24 10:59:24
CPUs Limit NTeams MaxTms NThrds Resrvd Free Locks Waits
10 100 4 12 100 13 68 106 590
10 100 6 12 100 12 63 4 6
10 100 6 12 100 12 63 0 0
10 100 7 12 100 12 62 1 1
10 100 7 12 100 12 62 0 0
10 100 7 12 100 12 58 1 5
10 100 7 12 100 12 58 0 0
Avoiding buffer manager thrashing
Operating system paging affects queries that need buffers which exceed the
free memory available. Some of this paging is necessary, especially as you
allocate more and more physical memory to your buffer caches. However, if
you overallocate the physical memory to your buffer caches, the operating
system paging occurs much more frequently, and it can cause your entire
system to thrash. The reverse is true as well: IQ thrashes if you do not allocate
enough memory to your buffer caches.