hi, I tested dp_hash for ovs group, and found that dp_hash can not well distributed, some buckets even can not be selected. In my testing environment, I have 11 buckets: group_id=131841,type=select,selection_method=dp_hash, bucket=bucket_id:51162,weight:100,actions=ct(commit,table=70,zone=2,exec(move:NXM_OF_ETH_SRC[]->NXM_NX_CT_LABEL[0..47],nat(dst=10.204.8.29:80))), bucket=bucket_id:42099,weight:100,actions=ct(commit,table=70,zone=2,exec(move:NXM_OF_ETH_SRC[]->NXM_NX_CT_LABEL[0..47],nat(dst=10.204.8.25:80))), bucket=bucket_id:53526,weight:100,actions=ct(commit,table=70,zone=2,exec(move:NXM_OF_ETH_SRC[]->NXM_NX_CT_LABEL[0..47],nat(dst=10.204.8.27:80))), bucket=bucket_id:12221,weight:100,actions=ct(commit,table=70,zone=2,exec(move:NXM_OF_ETH_SRC[]->NXM_NX_CT_LABEL[0..47],nat(dst=10.204.8.40:80))), bucket=bucket_id:2787,weight:100,actions=ct(commit,table=70,zone=2,exec(move:NXM_OF_ETH_SRC[]->NXM_NX_CT_LABEL[0..47],nat(dst=10.204.8.26:80))), bucket=bucket_id:18951,weight:100,actions=ct(commit,table=70,zone=2,exec(move:NXM_OF_ETH_SRC[]->NXM_NX_CT_LABEL[0..47],nat(dst=10.204.8.24:80))), bucket=bucket_id:32559,weight:100,actions=ct(commit,table=70,zone=2,exec(move:NXM_OF_ETH_SRC[]->NXM_NX_CT_LABEL[0..47],nat(dst=10.204.8.62:80))), bucket=bucket_id:35550,weight:100,actions=ct(commit,table=70,zone=2,exec(move:NXM_OF_ETH_SRC[]->NXM_NX_CT_LABEL[0..47],nat(dst=10.204.8.43:80))), bucket=bucket_id:9026,weight:100,actions=ct(commit,table=70,zone=2,exec(move:NXM_OF_ETH_SRC[]->NXM_NX_CT_LABEL[0..47],nat(dst=10.204.8.57:80))), bucket=bucket_id:26811,weight:100,actions=ct(commit,table=70,zone=2,exec(move:NXM_OF_ETH_SRC[]->NXM_NX_CT_LABEL[0..47],nat(dst=10.204.8.34:80)))
But about 3~5 buckets can not be selected always. In the function xlate_dp_hash_select_group(), I found the code: uint32_t mask = (1 << log_2_ceil(n_buckets)) - 1; uint32_t basis = 0xc2b73583 * (ctx->xin->flow.dp_hash & mask); uint32_t score = (hash_int(bucket->bucket_id, basis) & 0xffff) * bucket->weight; for the above formula, if n_buckets is 11, then there are totally 16 probabilities for basis. so how can we make sure the best score can well distributed in the 11 buckets? _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev
