Hello, Past days, I am trying to understand the VPP Bihash memory requirements & bucket sizing. It would good if someone points to reference. I have a capable system to scale up to 1 million connections.
Started experiment with few hundreds of connections. There will be thousands of add/deletes happening in the system, but caped to 100 at once. max_connections = 100, workers =4. hash table is per worker. I am using clib_bihash - 16_8 with initialized as nbuckets = max_connection/ BIHASH_KVP_PER_PAGE and *memory_size* =max_connection*1024. (1024.. I considered 1K of memory per connection). While experimenting, system is crashing at different places on couple of runs with out_of_memory in ~30min run * clib_bihash_add_del_16_8(hash delete)->make_working_copy_16_8->clib_mem_alloc_aligned->OOM. * clib_bihash_add_del_16_8(hash add) -> split_and_rehash_16_8(old_log2_pages=old_log2_pages@entry=2, new_log2_pages=new_log2_pages@entry=3) ->value_alloc_16_8->OOM My queries: * Assuming nbuckets is set correctly as per Bihash cookbook , How is the memory_size for hash deduced ? I think I have kept it low. Is there a guideline to deduce it considering this needs to scaled up to millions. * Can we minimize the hash collision resulting in rehash via nbuckets or memory_size ? Thanks, Shaligram
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