The AIX page replacement daemons scan memory a page at a time to find pages to evict in order to free up memory.
minperm and maxperm
These tunable parameters are used to indicate how much memory the AIX kernel should use to cache non-computational pages.
The maxperm tunable parameter indicates the maximum amount of memory that should be used to cache non-computational pages.
By default, maxperm is an "un-strict" limit, meaning that the limit can be exceeded.
Making maxperm an un-strict limit allows more non-computational files to be cached in memory when there is available free memory.
The maxperm limit can be made a "strict" limit by setting the strict_maxperm tunable parameter to 1.
When maxperm is a strict-limit, the kernel does not allow the number of non-computational pages to exceed maxperm, even if there is free memory available.
The minperm limit indicates the target minimum amount of memory that should be used for non-computational pages.
The number of non-computational pages is referred to as numperm:
The vmstat –v command displays the numperm value for a system as a percentage of a system’s real memory.
When the number of non-computational pages (numperm) is greater than or equal to maxperm, the AIX page replacement daemons strictly target non-computational pages.
When the number of non-computational pages (numperm) is less than or equal to minperm, the AIX page replacement daemons target both computational and non-computational pages
.
When the number of non-computational pages (numperm) is between minperm and maxperm, the lru_file_repage tunable parameter controls what kind of pages the AIX page replacement daemons should steal.
When numperm is between minperm and maxperm, the AIX page replacement daemons determine what type of pages to target based on their internal re-paging table when the lru_file_repage tunable parameter is set to 1.
# vmstat -v
20.0 minperm percentage <<- system’s minperm% setting
80.0 maxperm percentage <<- system’s maxperm% setting
minperm and maxperm
These tunable parameters are used to indicate how much memory the AIX kernel should use to cache non-computational pages.
The maxperm tunable parameter indicates the maximum amount of memory that should be used to cache non-computational pages.
By default, maxperm is an "un-strict" limit, meaning that the limit can be exceeded.
Making maxperm an un-strict limit allows more non-computational files to be cached in memory when there is available free memory.
The maxperm limit can be made a "strict" limit by setting the strict_maxperm tunable parameter to 1.
When maxperm is a strict-limit, the kernel does not allow the number of non-computational pages to exceed maxperm, even if there is free memory available.
The minperm limit indicates the target minimum amount of memory that should be used for non-computational pages.
The number of non-computational pages is referred to as numperm:
The vmstat –v command displays the numperm value for a system as a percentage of a system’s real memory.
When the number of non-computational pages (numperm) is greater than or equal to maxperm, the AIX page replacement daemons strictly target non-computational pages.
When the number of non-computational pages (numperm) is less than or equal to minperm, the AIX page replacement daemons target both computational and non-computational pages
.
When the number of non-computational pages (numperm) is between minperm and maxperm, the lru_file_repage tunable parameter controls what kind of pages the AIX page replacement daemons should steal.
When numperm is between minperm and maxperm, the AIX page replacement daemons determine what type of pages to target based on their internal re-paging table when the lru_file_repage tunable parameter is set to 1.
# vmstat -v
20.0 minperm percentage <<- system’s minperm% setting
80.0 maxperm percentage <<- system’s maxperm% setting
No comments:
Post a Comment