Harkrishn Patro c0267b3fa5
Optimize client memory usage tracking operation while client eviction is disabled (#11348)
## Issue
During the client input/output buffer processing, the memory usage is
incrementally updated to keep track of clients going beyond a certain
threshold `maxmemory-clients` to be evicted. However, this additional
tracking activity leads to unnecessary CPU cycles wasted when no
client-eviction is required. It is applicable in two cases.

* `maxmemory-clients` is set to `0` which equates to no client eviction
  (applicable to all clients)
* `CLIENT NO-EVICT` flag is set to `ON` which equates to a particular
  client not applicable for eviction.  

## Solution
* Disable client memory usage tracking during the read/write flow when
  `maxmemory-clients` is set to `0` or `client no-evict` is `on`.
  The memory usage is tracked only during the `clientCron` i.e. it gets
  periodically updated.
* Cleanup the clients from the memory usage bucket when client eviction
  is disabled.
* When the maxmemory-clients config is enabled or disabled at runtime,
  we immediately update the memory usage buckets for all clients (tested
  scanning 80000 took some 20ms)

Benchmark shown that this can improve performance by about 5% in
certain situations.

Co-authored-by: Oran Agra <oran@redislabs.com>
2022-12-07 08:26:56 +02:00
..

Redis Test Suite

The normal execution mode of the test suite involves starting and manipulating local redis-server instances, inspecting process state, log files, etc.

The test suite also supports execution against an external server, which is enabled using the --host and --port parameters. When executing against an external server, tests tagged external:skip are skipped.

There are additional runtime options that can further adjust the test suite to match different external server configurations:

Option Impact
--singledb Only use database 0, don't assume others are supported.
--ignore-encoding Skip all checks for specific encoding.
--ignore-digest Skip key value digest validations.
--cluster-mode Run in strict Redis Cluster compatibility mode.
--large-memory Enables tests that consume more than 100mb

Tags

Tags are applied to tests to classify them according to the subsystem they test, but also to indicate compatibility with different run modes and required capabilities.

Tags can be applied in different context levels:

  • start_server context
  • tags context that bundles several tests together
  • A single test context.

The following compatibility and capability tags are currently used:

Tag Indicates
external:skip Not compatible with external servers.
cluster:skip Not compatible with --cluster-mode.
large-memory Test that requires more than 100mb
tls:skip Not compatible with --tls.
needs:repl Uses replication and needs to be able to SYNC from server.
needs:debug Uses the DEBUG command or other debugging focused commands (like OBJECT REFCOUNT).
needs:pfdebug Uses the PFDEBUG command.
needs:config-maxmemory Uses CONFIG SET to manipulate memory limit, eviction policies, etc.
needs:config-resetstat Uses CONFIG RESETSTAT to reset statistics.
needs:reset Uses RESET to reset client connections.
needs:save Uses SAVE or BGSAVE to create an RDB file.

When using an external server (--host and --port), filtering using the external:skip tags is done automatically.

When using --cluster-mode, filtering using the cluster:skip tag is done automatically.

When not using --large-memory, filtering using the largemem:skip tag is done automatically.

In addition, it is possible to specify additional configuration. For example, to run tests on a server that does not permit SYNC use:

./runtest --host <host> --port <port> --tags -needs:repl