Hi Sage, I went through the tiering agent code base and here is my understanding on the agent behavior. Please let me know if that is correct.
1. Agent will be always in idle state if target_max_bytes or target_max_objects not set on the pool irrespective of other tiering params set in the pool. dirty_micro and full_micro will not be calculated if those two params are zero which is by default I guess. 2. Now, flush will be activated if dirty_micro is > flush_target. My understanding is, once it is activated it will iterate through all the dirty objects and flush all the dirty objects which is > cache_min_flush_age. Am I right ? 3. For the eviction, if full_micro > 1000000 , the mode set as TierAgentState::EVICT_MODE_FULL and all the clean objects are flushed. 4. if (full_micro > evict_target), the mode is set as TierAgentState::EVICT_MODE_SOME. In this scenario evict_effort is calculated and based on hit_set and temp calculation some clean objects are evicted. My question is , can we quantify this value ? For ex, if the target_full_ratio = 50%, once the eviction is triggered, what %objects will be evicted ? 5. Also, why we are multiplying with 1000000 always ? Is it because in the histogram it is positioned as 0..1000000 ? 6. I saw the cache_min_evict_age is not been used anywhere, am I missing anything ? 7. The cache_min_flush_age will only be applicable if the flush is triggered after crossing the dirty_threshold, right ? If dirty_threshold is not breached, the flush age param is never checked. I need to understand the behavior so that we can test the Cache tiering properly. Is there any behavior I am missing here which you want us to test out ? Thanks & Regards Somnath ________________________________ PLEASE NOTE: The information contained in this electronic mail message is intended only for the use of the designated recipient(s) named above. If the reader of this message is not the intended recipient, you are hereby notified that you have received this message in error and that any review, dissemination, distribution, or copying of this message is strictly prohibited. If you have received this communication in error, please notify the sender by telephone or e-mail (as shown above) immediately and destroy any and all copies of this message in your possession (whether hard copies or electronically stored copies).
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