>-----Original Message----- >From: Honnappa Nagarahalli [mailto:honnappa.nagaraha...@arm.com] >Sent: Wednesday, September 26, 2018 9:24 PM >To: Wang, Yipeng1 <yipeng1.w...@intel.com>; Richardson, Bruce ><bruce.richard...@intel.com> >Cc: dev@dpdk.org; mic...@digirati.com.br >Subject: RE: [PATCH v2 7/7] hash: use partial-key hashing > > >> +static inline void >> +get_buckets_index(const struct rte_hash *h, const hash_sig_t hash, >> +uint32_t *prim_bkt, uint32_t *sec_bkt, uint16_t *sig) { >> +/* >> + * We use higher 16 bits of hash as the signature value stored in table. >> + * We use the lower bits for the primary bucket >> + * location. Then we XOR primary bucket location and the signature >> + * to get the secondary bucket location. This is same as >> + * proposed in Bin Fan, et al's paper >> + * "MemC3: Compact and Concurrent MemCache with Dumber >> Caching and >> + * Smarter Hashing". The benefit to use >> + * XOR is that one could derive the alternative bucket location >> + * by only using the current bucket location and the signature. >> + */ >> +*sig = hash >> 16; >> + >> +*prim_bkt = hash & h->bucket_bitmask; >> +*sec_bkt = (*prim_bkt ^ *sig) & h->bucket_bitmask; } >> + >IMO, this function can be split into 2 - one for primary bucket index and >another for secondary bucket index. The secondary bucket >index calculation function can be used in functions ' >rte_hash_cuckoo_move_insert_mw' and ' rte_hash_cuckoo_make_space_mw'. > [Wang, Yipeng] I agree that breaking them down and use function call instead of explicit code will be easier for future extension, i.e. changing the algorithm, etc. I split the function into 3 in V4. Please check out.
>> -/** Signature of key that is stored internally. */ >> +/** >> + * A hash value that is used to generate signature stored in table and >> +the >> + * location the signature is stored. >> + */ >This is an external file. This documentation goes into the API guide. IMO, we >should change the comment to help the user. How about >changing this to 'hash value of the key'? > [Wang, Yipeng] Improved in V4. Please check! Thanks!
