Merged! Mathieu Desnoyers: > Buckets with many entries encountered in a hash table could cause it to > grow to a large size, beyond the scope for which this mechanism is > expected to play a role when node accounting is available. Indeed, when > the hash table grows to larger size, split-counter node accounting is > expected to deal with resize/shrink rather than relying on an heuristic > based on the largest bucket size. > > This is fixing an issue where we see hash tables sometimes reaching 65k > entries index (65536*8 = 524288 bytes) for a workload limited to adding > 1000 entries and then removing all of them, done in a loop (random > keys). > > Signed-off-by: Mathieu Desnoyers <[email protected]> > --- > diff --git a/src/common/hashtable/rculfhash.c > b/src/common/hashtable/rculfhash.c > index b430a3d..ebdc4ff 100644 > --- a/src/common/hashtable/rculfhash.c > +++ b/src/common/hashtable/rculfhash.c > @@ -726,9 +726,32 @@ void check_resize(struct cds_lfht *ht, unsigned long > size, uint32_t chain_len) > if (chain_len > 100) > dbg_printf("WARNING: large chain length: %u.\n", > chain_len); > - if (chain_len >= CHAIN_LEN_RESIZE_THRESHOLD) > - cds_lfht_resize_lazy_grow(ht, size, > - cds_lfht_get_count_order_u32(chain_len - > (CHAIN_LEN_TARGET - 1))); > + if (chain_len >= CHAIN_LEN_RESIZE_THRESHOLD) { > + int growth; > + > + /* > + * Ideal growth calculated based on chain length. > + */ > + growth = cds_lfht_get_count_order_u32(chain_len > + - (CHAIN_LEN_TARGET - 1)); > + if ((ht->flags & CDS_LFHT_ACCOUNTING) > + && (size << growth) >= (1UL << > COUNT_COMMIT_ORDER)) { > + /* > + * If ideal growth expands the hash table size > + * beyond the "small hash table" sizes, use the > + * maximum small hash table size to attempt > + * expanding the hash table. This only applies > + * when node accounting is available, otherwise > + * the chain length is used to expand the hash > + * table in every case. > + */ > + growth = COUNT_COMMIT_ORDER - > + cds_lfht_get_count_order_u32(size); > + if (growth <= 0) > + return; > + } > + cds_lfht_resize_lazy_grow(ht, size, growth); > + } > } > > static >
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