--- group: IO class --- The IO classes provide ability to control how data is cached with better granularity. Every IO can be analyzed on the fly to determine its attributes, attributes of an issuing process or a destination file. Using IO class configuration settings, Open CAS Linux may be tuned for a specific workload. The IO class mechanism can determine whether or not data shall be cached or with which priority it shall be evicted. -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- title: Setting occupancy limit id: occupancy --- It shall be possible to set a maximum size of an IO class. -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- title: Allowed occupancy values id: occupancy_allowed_values --- The product shall accept integer and fixed point values for a max size of an IO class in range from 0.00 to 1.00 and interpret them as a fraction of a cache size. -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- title: Default occupancy limit id: occupancy_default_limit --- When initializing a cache the software shall set IO class's max occupancy to 1.00. -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- title: Setting an occupancy limit on loading a cache id: occupancy_limit_on_load --- When a cache state is loaded, the occupancy limit for each IO class shall be set to the value used before the cache had been shut down. -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- title: Display an occupancy limit value id: occupancy_display_limit --- It shall be possible to display the currently set value of the occupancy limit for each configured ioclass. The value shall be displayed as a fraction of a cache size. -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- title: Respecting occupancy limit on a cache miss id: occupancy_respecting_limit_on_miss --- When an IO request is a miss and the target IO class has reached its occupancy limit, the software shall evict a number of missing cache blocks from the target IO class before inserting new data into it. -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- title: IO request to a disabled IO class id: occupancy_disabled_io_class --- When a target IO class max occupancy has been set to 0.00 the software shall submit IO requests in the Pass-Through mode. -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- title: Reassign cachelines to another IO class regardless of occupancy limit id: occupancy_limit_on_repart --- When an IO request is a hit and triggers reassigning a cache line to another IO class, the software shall reassign the cache line regardless of the target IO class's occupancy limit.