From patchwork Tue Jun 25 21:15:18 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Honnappa Nagarahalli X-Patchwork-Id: 55376 X-Patchwork-Delegate: thomas@monjalon.net Return-Path: X-Original-To: patchwork@dpdk.org Delivered-To: patchwork@dpdk.org Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 343321B9A1; Tue, 25 Jun 2019 23:15:44 +0200 (CEST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by dpdk.org (Postfix) with ESMTP id BAC8A1B993; Tue, 25 Jun 2019 23:15:40 +0200 (CEST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 03DDBC0A; Tue, 25 Jun 2019 14:15:40 -0700 (PDT) Received: from qc2400f-1.austin.arm.com (qc2400f-1.austin.arm.com [10.118.12.65]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E4F163F7D8; Tue, 25 Jun 2019 14:15:39 -0700 (PDT) From: Honnappa Nagarahalli To: yipeng1.wang@intel.com, sameh.gobriel@intel.com, bruce.richardson@intel.com, pablo.de.lara.guarch@intel.com, honnappa.nagarahalli@arm.com Cc: gavin.hu@arm.com, ruifeng.wang@arm.com, dev@dpdk.org, nd@arm.com, stable@dpdk.org Date: Tue, 25 Jun 2019 16:15:18 -0500 Message-Id: <20190625211520.43181-2-honnappa.nagarahalli@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190625211520.43181-1-honnappa.nagarahalli@arm.com> References: <20190625211520.43181-1-honnappa.nagarahalli@arm.com> Subject: [dpdk-dev] [PATCH 1/3] lib/hash: use ordered loads only if signature matches X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Relaxed signature comparison is done first. Further ordered loads are done only if the signature matches. Any false positives are caught by the full key comparison. Fixes: e605a1d36 ("hash: add lock-free r/w concurrency") Cc: stable@dpdk.org Signed-off-by: Honnappa Nagarahalli Reviewed-by: Gavin Hu Tested-by: Ruifeng Wang Acked-by: Yipeng Wang --- lib/librte_hash/rte_cuckoo_hash.c | 35 ++++++++++++++++++------------- 1 file changed, 21 insertions(+), 14 deletions(-) diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c index 953928f27..f37f6957d 100644 --- a/lib/librte_hash/rte_cuckoo_hash.c +++ b/lib/librte_hash/rte_cuckoo_hash.c @@ -1188,22 +1188,29 @@ search_one_bucket_lf(const struct rte_hash *h, const void *key, uint16_t sig, 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], + /* Signature comparison is done before the acquire-load + * of the key index to achieve better performance. + * Any false positives will be caught in full comparison + * of the key. + */ + if (bkt->sig_current[i] == sig) { + key_idx = __atomic_load_n(&bkt->key_idx[i], __ATOMIC_ACQUIRE); - if (bkt->sig_current[i] == sig && key_idx != EMPTY_SLOT) { - k = (struct rte_hash_key *) ((char *)keys + - key_idx * h->key_entry_size); - pdata = __atomic_load_n(&k->pdata, - __ATOMIC_ACQUIRE); + if (key_idx != EMPTY_SLOT) { + k = (struct rte_hash_key *) ((char *)keys + + key_idx * h->key_entry_size); + pdata = __atomic_load_n(&k->pdata, + __ATOMIC_ACQUIRE); - if (rte_hash_cmp_eq(key, k->key, h) == 0) { - if (data != NULL) - *data = pdata; - /* - * Return index where key is stored, - * subtracting the first dummy index - */ - return key_idx - 1; + if (rte_hash_cmp_eq(key, k->key, h) == 0) { + if (data != NULL) + *data = pdata; + /* + * Return index where key is stored, + * subtracting the first dummy index + */ + return key_idx - 1; + } } } }