From: Jerin Jacob <jerin.jacob@caviumnetworks.com>
To: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Cc: "bruce.richardson@intel.com" <bruce.richardson@intel.com>,
"pablo.de.lara.guarch@intel.com" <pablo.de.lara.guarch@intel.com>,
"dev@dpdk.org" <dev@dpdk.org>,
"hemant.agrawal@nxp.com" <hemant.agrawal@nxp.com>,
"chaozhu@linux.vnet.ibm.com" <chaozhu@linux.vnet.ibm.com>,
"yipeng1.wang@intel.com" <yipeng1.wang@intel.com>,
"dharmik.thakkar@arm.com" <dharmik.thakkar@arm.com>,
"gavin.hu@arm.com" <gavin.hu@arm.com>, "nd@arm.com" <nd@arm.com>
Subject: Re: [dpdk-dev] [PATCH 3/4] hash: remove memory orderings from rw-lock lookup fns
Date: Sat, 10 Nov 2018 08:51:29 +0000 [thread overview]
Message-ID: <20181110085100.GA14682@jerin> (raw)
In-Reply-To: <20181109163917.16845-4-honnappa.nagarahalli@arm.com>
-----Original Message-----
> Date: Fri, 9 Nov 2018 10:39:16 -0600
> From: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> To: bruce.richardson@intel.com, pablo.de.lara.guarch@intel.com
> CC: dev@dpdk.org, jerin.jacob@caviumnetworks.com, hemant.agrawal@nxp.com,
> chaozhu@linux.vnet.ibm.com, yipeng1.wang@intel.com,
> dharmik.thakkar@arm.com, gavin.hu@arm.com, honnappa.nagarahalli@arm.com,
> nd@arm.com
> Subject: [PATCH 3/4] hash: remove memory orderings from rw-lock lookup fns
> X-Mailer: git-send-email 2.17.1
>
>
> Remove the memory orderings from lookup functions using
> rw-lock.
> This is an intermediate commit meant to ease the
> review process.
>
> Fixes: e605a1d36 ("hash: add lock-free r/w concurrency")
> Cc: honnappa.nagarahalli@arm.com
>
> Suggested-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
> Reviewed-by: Ola Liljedahl <ola.liljedahl@arm.com>
> Reviewed-by: Gavin Hu <gavin.hu@arm.com>
> ---
> lib/librte_hash/rte_cuckoo_hash.c | 277 +++++++++++-------------------
> 1 file changed, 105 insertions(+), 172 deletions(-)
>
> diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c
> index e6b84c6bc..9390dc5e4 100644
> --- a/lib/librte_hash/rte_cuckoo_hash.c
> +++ b/lib/librte_hash/rte_cuckoo_hash.c
> @@ -1135,27 +1135,22 @@ search_one_bucket(const struct rte_hash *h, const void *key, uint16_t sig,
> void **data, const struct rte_hash_bucket *bkt)
> {
> int i;
> - uint32_t key_idx;
> - void *pdata;
> struct rte_hash_key *k, *keys = h->key_store;
>
> for (i = 0; i < RTE_HASH_BUCKET_ENTRIES; i++) {
> - key_idx = __atomic_load_n(&bkt->key_idx[i],
> - __ATOMIC_ACQUIRE);
> - if (bkt->sig_current[i] == sig && key_idx != EMPTY_SLOT) {
> + if (bkt->sig_current[i] == sig &&
> + bkt->key_idx[i] != EMPTY_SLOT) {
> k = (struct rte_hash_key *) ((char *)keys +
> - key_idx * h->key_entry_size);
> - pdata = __atomic_load_n(&k->pdata,
> - __ATOMIC_ACQUIRE);
> + bkt->key_idx[i] * h->key_entry_size);
>
> if (rte_hash_cmp_eq(key, k->key, h) == 0) {
> if (data != NULL)
> - *data = pdata;
> + *data = k->pdata;
> /*
> * Return index where key is stored,
> * subtracting the first dummy index
> */
> - return key_idx - 1;
> + return bkt->key_idx[i] - 1;
> }
> }
> }
> @@ -1201,7 +1196,6 @@ __rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key,
> {
> uint32_t prim_bucket_idx, sec_bucket_idx;
> struct rte_hash_bucket *bkt, *cur_bkt;
> - uint32_t cnt_b, cnt_a;
> int ret;
> uint16_t short_sig;
>
> @@ -1211,49 +1205,25 @@ __rte_hash_lookup_with_hash(const struct rte_hash *h, const void *key,
>
> __hash_rw_reader_lock(h);
>
> - do {
> - /* Load the table change counter before the lookup
> - * starts. Acquire semantics will make sure that
> - * loads in search_one_bucket are not hoisted.
> - */
> - cnt_b = __atomic_load_n(h->tbl_chng_cnt,
> - __ATOMIC_ACQUIRE);
> + /* Check if key is in primary location */
> + bkt = &h->buckets[prim_bucket_idx];
In original version, this bkt assignment is before to __hash_rw_reader_lock().
This causing performance issue in lookup 'hit' case.
Following change is fixing it.i.e bringing back to orginal version.
[master]83xx1.2[dpdk]# git diff
diff --git a/lib/librte_hash/rte_cuckoo_hash.c
b/lib/librte_hash/rte_cuckoo_hash.c
index 7e1a9ac96..bc8a55f0f 100644
--- a/lib/librte_hash/rte_cuckoo_hash.c
+++ b/lib/librte_hash/rte_cuckoo_hash.c
@@ -1204,10 +1204,11 @@ __rte_hash_lookup_with_hash_l(const struct
rte_hash *h, const void *key,
prim_bucket_idx = get_prim_bucket_index(h, sig);
sec_bucket_idx = get_alt_bucket_index(h, prim_bucket_idx,
short_sig);
- __hash_rw_reader_lock(h);
-
/* Check if key is in primary location */
bkt = &h->buckets[prim_bucket_idx];
+
+ __hash_rw_reader_lock(h);
+
ret = search_one_bucket_l(h, key, short_sig, data, bkt);
if (ret != -1) {
__hash_rw_reader_unlock(h);
Could you send the final version that needs to taken into tree.
i.e remove intermediate commits only for review purpose.
I can test it finally with that.
next prev parent reply other threads:[~2018-11-10 8:51 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-09 16:39 [dpdk-dev] [PATCH 0/4] hash: separate lf and rw lock lookup code paths Honnappa Nagarahalli
2018-11-09 16:39 ` [dpdk-dev] [PATCH 1/4] hash: prepare for lock-free and rw-lock separation Honnappa Nagarahalli
2018-11-09 16:39 ` [dpdk-dev] [PATCH 2/4] hash: remove rw-lock calls from lock-free functions Honnappa Nagarahalli
2018-11-09 16:39 ` [dpdk-dev] [PATCH 3/4] hash: remove memory orderings from rw-lock lookup fns Honnappa Nagarahalli
2018-11-10 8:51 ` Jerin Jacob [this message]
2018-11-10 18:58 ` Honnappa Nagarahalli
2018-11-09 16:39 ` [dpdk-dev] [PATCH 4/4] hash: separate lf and rw lock lookup code paths Honnappa Nagarahalli
2018-11-10 18:55 ` [dpdk-dev] [PATCH v2 0/1] " Honnappa Nagarahalli
2018-11-10 18:55 ` [dpdk-dev] [PATCH v2 1/1] " Honnappa Nagarahalli
2018-11-11 7:48 ` Jerin Jacob
2018-11-13 16:37 ` Thomas Monjalon
2018-11-11 21:43 ` Wang, Yipeng1
2018-11-12 4:50 ` Honnappa Nagarahalli
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