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From: "Wang, Yipeng1" <yipeng1.wang@intel.com>
To: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>,
	"Gobriel, Sameh" <sameh.gobriel@intel.com>,
	"Richardson, Bruce" <bruce.richardson@intel.com>,
	"De Lara Guarch, Pablo" <pablo.de.lara.guarch@intel.com>
Cc: "gavin.hu@arm.com" <gavin.hu@arm.com>,
	"ruifeng.wang@arm.com" <ruifeng.wang@arm.com>,
	"dev@dpdk.org" <dev@dpdk.org>, "nd@arm.com" <nd@arm.com>,
	"stable@dpdk.org" <stable@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH 1/3] lib/hash: use ordered loads only if signature matches
Date: Fri, 28 Jun 2019 18:04:53 +0000	[thread overview]
Message-ID: <D2C4A16CA39F7F4E8E384D204491D7A673EC7050@ORSMSX104.amr.corp.intel.com> (raw)
In-Reply-To: <20190625211520.43181-2-honnappa.nagarahalli@arm.com>

>-----Original Message-----
>From: Honnappa Nagarahalli [mailto:honnappa.nagarahalli@arm.com]
>Sent: Tuesday, June 25, 2019 2:15 PM
>To: Wang, Yipeng1 <yipeng1.wang@intel.com>; Gobriel, Sameh <sameh.gobriel@intel.com>; Richardson, Bruce
><bruce.richardson@intel.com>; De Lara Guarch, Pablo <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
>Subject: [PATCH 1/3] lib/hash: use ordered loads only if signature matches
>
>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.
[Wang, Yipeng] add: This commit improves lookup performance.
>
>Fixes: e605a1d36 ("hash: add lock-free r/w concurrency")
>Cc: stable@dpdk.org
>
>Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
>Reviewed-by: Gavin Hu <gavin.hu@arm.com>
>Tested-by: Ruifeng Wang <ruifeng.wang@arm.com>
>---
> 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.
>+		 */
[Wang, Yipeng] 
A bit more explanation would be helpful for future understanding of the code:
"Signature comparison is done ... performance.
Although this could accidentally cause the reader to read an old signature while the key_idx
is updated to a new key's,  any false positive will be .... of the key."

Otherwise:
Acked-by: Yipeng Wang <yipeng1.wang@intel.com>

  reply	other threads:[~2019-06-28 18:05 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-25 21:15 [dpdk-dev] [PATCH 0/3] lib/hash: perf improvements for lock-free Honnappa Nagarahalli
2019-06-25 21:15 ` [dpdk-dev] [PATCH 1/3] lib/hash: use ordered loads only if signature matches Honnappa Nagarahalli
2019-06-28 18:04   ` Wang, Yipeng1 [this message]
2019-06-25 21:15 ` [dpdk-dev] [PATCH 2/3] lib/hash: load pData after full key compare Honnappa Nagarahalli
2019-06-28 18:40   ` Wang, Yipeng1
2019-07-02  4:35     ` Honnappa Nagarahalli
2019-07-04  0:39       ` Wang, Yipeng1
2019-07-05  5:33         ` Honnappa Nagarahalli
2019-07-08 16:44           ` Wang, Yipeng1
2019-06-25 21:15 ` [dpdk-dev] [PATCH 3/3] lib/hash: adjust tbl_chng_cnt position Honnappa Nagarahalli
2019-06-28 18:50   ` Wang, Yipeng1
2019-07-02 17:23     ` Honnappa Nagarahalli
2019-07-04  0:52       ` Wang, Yipeng1
2019-07-02 21:16 ` [dpdk-dev] [PATCH v2 0/2] lib/hash: perf improvements for lock-free Honnappa Nagarahalli
2019-07-02 21:16   ` [dpdk-dev] [PATCH v2 1/2] lib/hash: use ordered loads only if signature matches Honnappa Nagarahalli
2019-07-02 21:16   ` [dpdk-dev] [PATCH v2 2/2] lib/hash: load pData after full key compare Honnappa Nagarahalli
2019-07-04 11:13   ` [dpdk-dev] [PATCH v2 0/2] lib/hash: perf improvements for lock-free Jerin Jacob Kollanukkaran
2019-07-05  6:08     ` Honnappa Nagarahalli
2019-07-04 16:09   ` Thomas Monjalon
2019-07-05  6:14     ` Honnappa Nagarahalli
2019-07-05  6:29       ` Thomas Monjalon
2019-07-08 16:51     ` Wang, Yipeng1
2019-07-08 18:10       ` Thomas Monjalon

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