github/open-cas-linux
2
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Requirements for occupancy per ioclass

Browse Source 
Signed-off-by: Michal Mielewczyk <michal.mielewczyk@intel.com>
This commit is contained in:
Michal Mielewczyk 2021-02-12 03:34:29 -05:00
parent 65796836e4
commit dcdcc658b4
1 changed files with 83 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

83
doc/requirements/io_class Normal file
View File

@ -0,0 +1,83 @@
---
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.