Hi Avinash, > -----Original Message----- > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Yeddula, Avinash > Sent: Monday, October 12, 2015 6:03 PM > To: Dumitrescu, Cristian; dev at dpdk.org; Bly, Mike > Subject: Re: [dpdk-dev] DPDK hash function related question > > Hi Cristian, > I have configured the hash function and it compile fine with "warnings". Since > librte_hash vs librte_table is 32bit vs 64bit. > > librte_hash library : > /** Type of function that can be used for calculating the hash value. */ > typedef uint32_t (*rte_hash_function)(const void *key, uint32_t key_len, > uint32_t init_val); > > librte_table library: > typedef uint64_t (*rte_table_hash_op_hash) (void *key, uint32_t > key_size, uint64_t seed); > > I could use one of these hash functions. This is one option, but our first > priority is to use crc hash or cukoo hash.
Mind that cuckoo hash is not a hash function, but a method for resolving collisions in a hash table. > https://github.com/scylladb/dpdk/blob/master/examples/ip_pipeline/pipeli > ne/hash_func.h > > We do not want to have those warning in our code. What do you suggest ? > > Thanks > -Avinash > > -----Original Message----- > From: Dumitrescu, Cristian [mailto:cristian.dumitrescu at intel.com] > Sent: Tuesday, September 22, 2015 3:05 AM > To: Yeddula, Avinash; dev at dpdk.org; Bly, Mike > Subject: RE: DPDK hash function related question > > Hi Avinash, > > Yes, the hash function is configurable. > > Are you using a DPDK release older than 2.1? In DPDK we moved away from > test_hash to CRC-based hashes. Please take a look at DPDK release 2.1 > examples/ip_pipeline application: in pipeline_flow_classification_be.c, we > use CRC-based hash functions defined in file hash_func.h from the same > folder. > > Regards, > Cristian > > > -----Original Message----- > > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Yeddula, Avinash > > Sent: Tuesday, September 22, 2015 1:34 AM > > To: dev at dpdk.org; Bly, Mike > > Subject: [dpdk-dev] DPDK hash function related question > > > > Hello All, > > > > I'm DPDK extensible bucket hash in the rte_table library of packet > > framework. My question is related to the actual hash function that > > computes the hash signature. > > > > All the available examples have initialized it to test_hash. I do not see > > any > > hash function available in rte_table library , that computes the > > actual signature > > > > > > > > struct rte_table_hash_ext_params hash_table_params = { > > > > .key_size = TABLE_ENTRY_KEY_SIZE, > > > > .n_keys = TABLE_MAX_SIZE, > > > > .n_buckets = TABLE_MAX_BUCKET_COUNT, > > > > .n_buckets_ext = TABLE_MAX_EXT_BUCKET_COUNT, > > > > .f_hash = test_hash, > > > > .seed = 0, > > > > .signature_offset = 0; > > > > .key_offset = __builtin_offsetof(struct metadata_t, tbl_key), > > > > }; > > > > > > > > So, I wanted to use hash functions from DPDK rte_hash library. This is > > what I'm doing and looking at the code this looks ok to me. > > > > I'm at least a week or 2 away from testing this part of the code. I > > wanted to confirm that, there is no fundamental flaw in using the DPDK > > rte_hash library and rte_table library like this. Could someone confirm this > please ? > > > > > > > > #define DEFAULT_HASH_FUNC rte_hash_crc > > > > > > > > struct rte_table_hash_ext_params hash_table_params = { > > > > .key_size = TABLE_ENTRY_KEY_SIZE, > > > > .n_keys = TABLE_MAX_SIZE, > > > > .n_buckets = TABLE_MAX_BUCKET_COUNT, > > > > .n_buckets_ext = TABLE_MAX_EXT_BUCKET_COUNT, > > > > .f_hash = DEFAULT_HASH_FUNC , > > > > .seed = 0, > > > > .signature_offset = 0; > > > > .key_offset = __builtin_offsetof(struct metadata_t, tbl_key), > > > > }; > > > > > > > > Thanks > > > > -Avinash > > >
