hi, want to update you guys with the current status of the crimson-osd. where we are: we have ported/adapted messenger, mon client, config, logging, perf counter to seastar framework. based on them, we are able to boot[0] the crimson-osd now. by "boot", i mean, crimson-osd can be discovered by monitor after it starts. so, we still don't have anything to test with, aside from the messenger. the next steps: to implement the i/o path to serve the read requests with the memstore using the 1-to-1 threading model. the reason why we want to prioritize this is to understand the behavior of crimson-osd as soon as possible with minimal efforts. so, the focus of current stage of this project will be: - the 1:1 mapping implementation. as 1:1 mapping is easier to design and debugging, and there are a lot valuable insights in the 1:1 versus m:n discussion. it seems the performance of 1:1 model is not likely to suffer from any obvious problems. so we think it can be used to present the best performance we can achieve using share-nothing architecture. - read path only. but we need to be sure we don't skip any critical step that could impact the performance in the i/o path in the future. this will help us to get an authentic benchmark result. - memstore only. the access to memstore is practically very fast and non-blocking.so we can read/write it without worrying about how to confine bluestore in an alien world and how to cater for its needs for the facilities only available in alien world. once we have the read path ready, and we have a good understanding of it in the perspective of its performance, and design. we will be better prepared for implementing the write path and for adding more features back to crimson-osd. as to the methodology of benchmarking, we want to have an apple-to-apple comparison between crimson-osd and existing osd, we could start $(npro) instances of crimson-osd side by side, and to profile it. and on the same box, the same number of existing-osd instances will be used as the controlled group. if i am missing anything or apparently wrong. please point it out. thanks, -- [0] https://github.com/ceph/ceph/pull/25304 -- Regards Kefu Chai
