From: Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>
To: Yipeng Wang <yipeng1.wang@intel.com>,
"bruce.richardson@intel.com" <bruce.richardson@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
"michel@digirati.com.br" <michel@digirati.com.br>,
nd <nd@arm.com>
Subject: Re: [dpdk-dev] [PATCH v2 0/7] hash: add extendable bucket and partial key hashing
Date: Thu, 27 Sep 2018 04:23:10 +0000 [thread overview]
Message-ID: <AM6PR08MB3672ED8AC62B0C573756E85F98140@AM6PR08MB3672.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <1537550255-252066-1-git-send-email-yipeng1.wang@intel.com>
> -----Original Message-----
> From: Yipeng Wang <yipeng1.wang@intel.com>
> Sent: Friday, September 21, 2018 12:17 PM
> To: bruce.richardson@intel.com
> Cc: dev@dpdk.org; yipeng1.wang@intel.com; michel@digirati.com.br;
> Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>
> Subject: [PATCH v2 0/7] hash: add extendable bucket and partial key hashing
>
> The first four commits of the patch set try to fix small issues of previous code.
>
> The other commits make two major optimizations over the current rte_hash
> library.
>
> First, it adds Extendable Bucket Table feature: a new structure that can
> accommodate keys that failed to get inserted into the main hash table due to
> the unlikely event of excessive hash collisions. The hash table buckets will get
> extended using a linked list to host these keys. This new design will guarantee
> insertion of 100% of the keys for a given hash table size with minimal
> overhead. A new flag value is added for user to indicate if the extendable
> bucket feature should be enabled or not. The linked list buckets is similar
> concept to the extendable bucket hash table in packet framework.
> In details, for insertion, the linked buckets will be used to store the keys that
> fail to get in the primary and the secondary bucket and the cuckoo path could
> not find an empty location for the maximum path length (small probability).
> For lookup, the key is checked first in the primary, then the secondary, then if
> the secondary is extended the linked list is traversed for a possible match.
>
> Second, the patch set changes the current hashing algorithm to be "partial-
> key hashing". Partial-key hashing is the concept from Bin Fan, et al.'s paper
> "MemC3: Compact and Concurrent MemCache with Dumber Caching and
> Smarter Hashing".
I read this paper (but not the papers in references). My understanding is that the existing algorithm already uses 'partial-key hashing'. This patch set is not adding the 'partial-key hashing' feature. Instead it is reducing the size of the signature ('tag' as referred in the paper) from 32 to 16b.
Please let me know if I have not understood this correct.
> Instead of storing both 32-bit signature and alternative
> signature in the bucket, we only store a small 16-bit signature and calculate
> the alternative bucket index by XORing the signature with the current bucket
> index.
According to the referenced paper, the signature ('tag') reduces the number of accesses to the keys, thus improving the performance.
But, if we reduce the size of the signature from 32b to 16b, it will result in higher probability of false matches on the signature. This in turn will increase the number of accesses to keys. Have you run any performance benchmarks and compared the numbers with the existing code? Is it possible to share the numbers?
> This doubles the hash table memory efficiency since now one bucket only
> occupies one cache line instead of two in the original design.
Agree, reduced memory footprint should help increase the performance.
>
> V1->V2:
> 1. hash: Rewrite rte_hash_get_last_bkt to be more concise.
> 2. hash: Reorder the rte_hash struct to align cache line better.
> 3. test: Minor changes in auto test to add key insertion failure check during
> iteration test.
> 4. test: Add new commit to fix read-write test non-consecutive core issue.
> 4. hash: Add a new commit to remove unnecessary code introduced by
> previous patches.
> 5. hash: Comments improvement and coding style improvements over
> multiple places.
>
> Signed-off-by: Yipeng Wang <yipeng1.wang@intel.com>
>
> Yipeng Wang (7):
> test/hash: fix bucket size in hash perf test
> test/hash: more accurate hash perf test output
> test/hash: fix rw test with non-consecutive cores
> hash: fix unnecessary code
> hash: add extendable bucket feature
> test/hash: implement extendable bucket hash test
> hash: use partial-key hashing
>
> lib/librte_hash/rte_cuckoo_hash.c | 516 +++++++++++++++++++++++++++------
> -----
> lib/librte_hash/rte_cuckoo_hash.h | 13 +-
> lib/librte_hash/rte_hash.h | 8 +-
> test/test/test_hash.c | 151 ++++++++++-
> test/test/test_hash_perf.c | 126 +++++++---
> test/test/test_hash_readwrite.c | 78 +++---
> 6 files changed, 672 insertions(+), 220 deletions(-)
>
> --
> 2.7.4
next prev parent reply other threads:[~2018-09-27 4:23 UTC|newest]
Thread overview: 107+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-06 17:09 [dpdk-dev] [PATCH v1 0/5] hash: add extendable bucket and partial-key hashing Yipeng Wang
2018-09-06 17:09 ` [dpdk-dev] [PATCH v1 1/5] test: fix bucket size in hash table perf test Yipeng Wang
2018-09-06 17:09 ` [dpdk-dev] [PATCH v1 2/5] test: more accurate hash table perf test output Yipeng Wang
2018-09-06 17:09 ` [dpdk-dev] [PATCH v1 3/5] hash: add extendable bucket feature Yipeng Wang
2018-09-06 17:09 ` [dpdk-dev] [PATCH v1 4/5] test: implement extendable bucket hash test Yipeng Wang
2018-09-06 17:09 ` [dpdk-dev] [PATCH v1 5/5] hash: use partial-key hashing Yipeng Wang
2018-09-21 17:17 ` [dpdk-dev] [PATCH v2 0/7] hash: add extendable bucket and partial key hashing Yipeng Wang
2018-09-21 17:17 ` [dpdk-dev] [PATCH v2 1/7] test/hash: fix bucket size in hash perf test Yipeng Wang
2018-09-26 10:04 ` Bruce Richardson
2018-09-27 3:39 ` Wang, Yipeng1
2018-09-27 4:23 ` Honnappa Nagarahalli
2018-09-29 0:31 ` Wang, Yipeng1
2018-09-21 17:17 ` [dpdk-dev] [PATCH v2 2/7] test/hash: more accurate hash perf test output Yipeng Wang
2018-09-26 10:07 ` Bruce Richardson
2018-09-21 17:17 ` [dpdk-dev] [PATCH v2 3/7] test/hash: fix rw test with non-consecutive cores Yipeng Wang
2018-09-26 11:02 ` Bruce Richardson
2018-09-27 3:40 ` Wang, Yipeng1
2018-09-26 11:13 ` Bruce Richardson
2018-09-21 17:17 ` [dpdk-dev] [PATCH v2 4/7] hash: fix unnecessary code Yipeng Wang
2018-09-26 12:55 ` Bruce Richardson
2018-09-21 17:17 ` [dpdk-dev] [PATCH v2 5/7] hash: add extendable bucket feature Yipeng Wang
2018-09-27 4:23 ` Honnappa Nagarahalli
2018-09-27 11:15 ` Bruce Richardson
2018-09-27 11:27 ` Ananyev, Konstantin
2018-09-27 12:27 ` Bruce Richardson
2018-09-27 12:33 ` Ananyev, Konstantin
2018-09-27 19:21 ` Honnappa Nagarahalli
2018-09-28 17:35 ` Wang, Yipeng1
2018-09-29 21:09 ` Honnappa Nagarahalli
2018-09-29 1:10 ` Wang, Yipeng1
2018-10-01 20:56 ` Honnappa Nagarahalli
2018-10-02 1:56 ` Wang, Yipeng1
2018-09-21 17:17 ` [dpdk-dev] [PATCH v2 6/7] test/hash: implement extendable bucket hash test Yipeng Wang
2018-09-27 4:24 ` Honnappa Nagarahalli
2018-09-29 0:50 ` Wang, Yipeng1
2018-09-21 17:17 ` [dpdk-dev] [PATCH v2 7/7] hash: use partial-key hashing Yipeng Wang
2018-09-27 4:24 ` Honnappa Nagarahalli
2018-09-29 0:55 ` Wang, Yipeng1
2018-09-26 12:57 ` [dpdk-dev] [PATCH v2 0/7] hash: add extendable bucket and partial key hashing Bruce Richardson
2018-09-27 3:41 ` Wang, Yipeng1
2018-09-27 4:23 ` Honnappa Nagarahalli [this message]
2018-09-29 0:46 ` Wang, Yipeng1
2018-09-26 12:54 ` [dpdk-dev] [PATCH v3 0/5] hash: fix multiple issues Yipeng Wang
2018-09-26 12:54 ` [dpdk-dev] [PATCH v3 1/5] test/hash: fix bucket size in hash perf test Yipeng Wang
2018-09-27 11:17 ` Bruce Richardson
2018-09-26 12:54 ` [dpdk-dev] [PATCH v3 2/5] test/hash: more accurate hash perf test output Yipeng Wang
2018-09-26 12:54 ` [dpdk-dev] [PATCH v3 3/5] test/hash: fix rw test with non-consecutive cores Yipeng Wang
2018-09-27 11:18 ` Bruce Richardson
2018-09-26 12:54 ` [dpdk-dev] [PATCH v3 4/5] test/hash: fix missing file in meson build file Yipeng Wang
2018-09-27 11:22 ` Bruce Richardson
2018-09-26 12:54 ` [dpdk-dev] [PATCH v3 5/5] hash: fix unused define Yipeng Wang
2018-09-28 14:11 ` [dpdk-dev] [PATCH v4 0/5] hash: fix multiple issues Yipeng Wang
2018-09-28 14:11 ` [dpdk-dev] [PATCH v4 1/5] test/hash: fix bucket size in hash perf test Yipeng Wang
2018-10-01 20:28 ` Honnappa Nagarahalli
2018-09-28 14:11 ` [dpdk-dev] [PATCH v4 2/5] test/hash: more accurate hash perf test output Yipeng Wang
2018-09-28 14:11 ` [dpdk-dev] [PATCH v4 3/5] test/hash: fix rw test with non-consecutive cores Yipeng Wang
2018-09-28 14:11 ` [dpdk-dev] [PATCH v4 4/5] test/hash: fix missing file in meson build file Yipeng Wang
2018-09-28 14:11 ` [dpdk-dev] [PATCH v4 5/5] hash: fix unused define Yipeng Wang
2018-10-25 22:04 ` [dpdk-dev] [PATCH v4 0/5] hash: fix multiple issues Thomas Monjalon
2018-09-26 20:26 ` [dpdk-dev] [PATCH v3 0/3] hash: add extendable bucket and partial key hashing Yipeng Wang
2018-09-26 20:26 ` [dpdk-dev] [PATCH v3 1/3] hash: add extendable bucket feature Yipeng Wang
2018-09-26 20:26 ` [dpdk-dev] [PATCH v3 2/3] test/hash: implement extendable bucket hash test Yipeng Wang
2018-09-26 20:26 ` [dpdk-dev] [PATCH v3 3/3] hash: use partial-key hashing Yipeng Wang
2018-09-28 17:23 ` [dpdk-dev] [PATCH v4 0/4] hash: add extendable bucket and partial key hashing Yipeng Wang
2018-09-28 17:23 ` [dpdk-dev] [PATCH v4 1/4] hash: fix race condition in iterate Yipeng Wang
2018-10-01 20:23 ` Honnappa Nagarahalli
2018-10-02 0:17 ` Wang, Yipeng1
2018-10-02 4:26 ` Honnappa Nagarahalli
2018-10-02 23:53 ` Wang, Yipeng1
2018-09-28 17:23 ` [dpdk-dev] [PATCH v4 2/4] hash: add extendable bucket feature Yipeng Wang
2018-10-02 3:58 ` Honnappa Nagarahalli
2018-10-02 23:39 ` Wang, Yipeng1
2018-10-03 4:37 ` Honnappa Nagarahalli
2018-10-03 15:08 ` Stephen Hemminger
2018-10-03 15:08 ` Stephen Hemminger
2018-10-03 16:53 ` Wang, Yipeng1
2018-10-03 17:59 ` Honnappa Nagarahalli
2018-10-04 1:22 ` Wang, Yipeng1
2018-09-28 17:23 ` [dpdk-dev] [PATCH v4 3/4] test/hash: implement extendable bucket hash test Yipeng Wang
2018-10-01 19:53 ` Honnappa Nagarahalli
2018-09-28 17:23 ` [dpdk-dev] [PATCH v4 4/4] hash: use partial-key hashing Yipeng Wang
2018-10-01 20:09 ` Honnappa Nagarahalli
2018-10-03 19:05 ` [dpdk-dev] [PATCH v4 0/4] hash: add extendable bucket and partial key hashing Dharmik Thakkar
2018-10-01 18:34 ` [dpdk-dev] [PATCH v5 " Yipeng Wang
2018-10-01 18:34 ` [dpdk-dev] [PATCH v5 1/4] hash: fix race condition in iterate Yipeng Wang
2018-10-02 17:26 ` Honnappa Nagarahalli
2018-10-01 18:35 ` [dpdk-dev] [PATCH v5 2/4] hash: add extendable bucket feature Yipeng Wang
2018-10-01 18:35 ` [dpdk-dev] [PATCH v5 3/4] test/hash: implement extendable bucket hash test Yipeng Wang
2018-10-01 18:35 ` [dpdk-dev] [PATCH v5 4/4] hash: use partial-key hashing Yipeng Wang
2018-10-02 20:52 ` Dharmik Thakkar
2018-10-03 0:43 ` Wang, Yipeng1
2018-10-03 19:10 ` [dpdk-dev] [PATCH v5 0/4] hash: add extendable bucket and partial key hashing Dharmik Thakkar
2018-10-04 0:36 ` Wang, Yipeng1
2018-10-04 16:35 ` [dpdk-dev] [PATCH v6 " Yipeng Wang
2018-10-04 16:35 ` [dpdk-dev] [PATCH v6 1/4] hash: fix race condition in iterate Yipeng Wang
2018-10-04 16:35 ` [dpdk-dev] [PATCH v6 2/4] hash: add extendable bucket feature Yipeng Wang
2018-10-04 16:35 ` [dpdk-dev] [PATCH v6 3/4] test/hash: implement extendable bucket hash test Yipeng Wang
2018-10-04 16:35 ` [dpdk-dev] [PATCH v6 4/4] hash: use partial-key hashing Yipeng Wang
2018-10-10 21:27 ` [dpdk-dev] [PATCH v7 0/4] hash: add extendable bucket and partial key hashing Yipeng Wang
2018-10-10 21:27 ` [dpdk-dev] [PATCH v7 1/4] hash: fix race condition in iterate Yipeng Wang
2018-10-10 21:27 ` [dpdk-dev] [PATCH v7 2/4] hash: add extendable bucket feature Yipeng Wang
2018-10-10 21:27 ` [dpdk-dev] [PATCH v7 3/4] test/hash: implement extendable bucket hash test Yipeng Wang
2018-10-10 21:27 ` [dpdk-dev] [PATCH v7 4/4] hash: use partial-key hashing Yipeng Wang
2018-10-16 18:47 ` [dpdk-dev] [PATCH] doc: update release note for hash library Yipeng Wang
2018-10-17 20:09 ` Honnappa Nagarahalli
2018-10-25 18:45 ` Wang, Yipeng1
2018-10-25 23:07 ` Thomas Monjalon
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