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Merge pull request #708 from mmichal10/cleaning-reqs

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doc: Requirements for cleaning
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Robert Baldyga 2021-05-26 23:48:07 +02:00 committed by GitHub
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---
group: Cleaning
---
Data in cache before being written to a primary storage is called dirty. Flushing
may be deferred to some point in the future. Cleaning is a background process of
flushing dirty data to a primary storage and depending on the needs it can be
performed using different strategies. These strategies are referred to as cleaning
policies.
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title: Available cleaning policies
id: available_policies
---
The following cleaning policies shall be available:
1. NOP
2. ALRU
3. ACP
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title: NOP cleaning policy
id: nop
---
When NOP is set as the active cleaning policy the product shall not perform
background cleaning.
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title: ALRU wake up interval when IO requests are detected
id: alru_wake_up_on_io
---
When ALRU is set as the active cleaning policy and the time passed since the last
IO request to the cache instance is lower than ACTIVITY_THRESHOLD the product
shall put the background worker to sleep for WAKE_UP.
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title: ALRU flush conditions
id: alru_flush_conditions
---
When ALRU is set as the active cleaning policy the product shall flush dirty cache
lines which had not been written for at least STALENESS_TIME.
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title: ALRU wake up interval when nothing to flush
id: alru_wake_up_on_no_flush
---
When ALRU is set as the active cleaning policy and eligible cache lines to flush
had not been found the product shall put the background worker to sleep for WAKE_UP.
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title: ALRU max flushed cache lines
id: alru_max_buffers
---
When ALRU is set as the active cleaning policy the product shall flush at most
FLUSH_MAX_BUFFERS dirty cache lines in a single iteration.
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title: ALRU valid wake up values
id: alru_valid_wake_up
---
The product shall accept WAKE_UP values in range from 1 second to 3600 seconds
inclusive.
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title: ALRU valid staleness time values
id: alru_valid_staleness_time
---
The product shall accept STALENESS_TIME values in range from 1 second to 3600
seconds inclusive.
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title: ALRU valid activity threshold values
id: alru_valid_activity_threshold
---
The product shall accept ACTIVITY_THRESHOLD values in range from 0 to 1000000
milliseconds inclusive.
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title: ALRU valid flush max buffers values
id: alru_valid_flush_max_buffers
---
The product shall accept FLUSH_MAX_BUFFERS values in range from 1 to 10000 cache
lines inclusive.
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title: ACP cleaning policy
id: acp
---
When ACP is set as the active cleaning policy the product shall flush at most
FLUSH_MAX_BUFFERS cache lines in WAKE_UP intervals.
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title: ACP valid flush max buffers values
id: acp_valid_flush_max_buffers
---
The product shall accept FLUSH_MAX_BUFFERS values in range from 1 to 10000 cache
lines inclusive.
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title: ACP valid wake up time values
id: acp_valid_wake_up
---
The product shall accept WAKE_UP values in range from 0 to 10000 milliseconds
inclusive.
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title: ALRU display configured parameters
id: alru_display_parameters
---
The product shall allow to display values of ALRU parameters.
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title: ACP display configured parameters
id: acp_display_parameters
---
The product shall allow to display values of ACP parameters.
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title: Display configured policy
id: display_policy
---
The product shall allow to display currently configured cleaning policy.
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title: Policy on cache load
id: load_policy
---
When a cache state is loaded the product shall restore the cleaning policy used
before the cache shut down.
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title: ALRU parameters on cache load
id: alru_parameters_load
---
When a cache state is loaded the product shall restore the ALRU parameters to the
values used before the cache shut down.
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title: ACP parameters on cache load
id: acp_parameters_load
---
When a cache state is loaded the product shall restore the ACP parameters to the
values used before the cache shut down.
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title: ALRU default parameters
id: alru_default
---
The product shall initialize ALRU with the following parameters:
1. WAKE_UP equal to 20 seconds
2. STALENESS_TIME equal to 120 seconds
3. FLUSH_MAX_BUFFERS equal to 100 cache lines
4. ACTIVITY_THRESHOLD equal to 10000 milliseconds
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title: ACP default parameters
id: acp_default
---
The product shall initialize ACP with the following parameters:
1. WAKE_UP equal to 10 milliseconds
2. FLUSH_MAX_BUFFERS equal to 128 cache lines
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title: Default cleaning policy
id: default_policy
---
When initializing a new cache instance the product shall set ALRU as the default
cleaning policy.
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title: Setting cleaning policy in runtime
id: change_in_runtime
---
The product shall allow to change cleaning policy in runtime.
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title: Setting cleaning policy parameters in runtime
id: change_parameters_in_runtime
---
The product shall allow to change cleaning policy parameters in runtime.