Ceph » rgw

This tracker issue is a TODO list for the remaining tasks for the D3N DataCache following the initial commit.

1. debug `s3_tests` failures when `--rgw_compression=zlib`
2. debug s3_tests failures when `rgw_max_chunk_size != rgw_obj_stripe_size`
3. check if `-o rgw_enable_ops_log=true` is still necesary for D3N operation
4. does `D3nL1CacheRequest` need to be allocated on the heap? (https://github.com/ceph/ceph/pull/36266/#discussion_r655622746)
5. does the `aiocb` ilabaio callback structure needs to allocated on the heap? (https://github.com/ceph/ceph/pull/36266/#discussion_r655617364)
6. check if changing the `d3n_cache_map` from std::unordered_map to `boost::intrusive::list` improves eviction performance (https://github.com/ceph/ceph/pull/36266/#discussion_r494300389)
7. add perf counters and radosgw-admin & rest facilities to check the amount of d3n cache data stored and object/byte hit ratios

additional items from github comment: https://github.com/ceph/ceph/pull/36266/#pullrequestreview-697467454

• support non-yielding version of rgw::d3n_cache_op()
• optimize random eviction
• user docs (high-level feature description, setup instructions, config options)

additional todo items:

• add cache-in algorithm selection, ex:
  option to populate cache on PUT
  option to populate cache only after a certain number of gets during the specified time window
• Predictive Cache Analisis - While the Cache is disabled, analyze the load and captures Cache statistics to observes what the Cache hit ratios might be with the Cache enabled (Credit Or)
• Upstreaming of the L2 PR
• logs cleanup and rewording for consistency
• Cleanup refactor to minimize the number is #incude's related to D3N code to minimum and move as much as possible of the D3N code from .h files to .cpp files to reduce compile time