From: "Wang, Yipeng1" <yipeng1.wang@intel.com>
To: Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>,
"Richardson, Bruce" <bruce.richardson@intel.com>
Cc: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
"dev@dpdk.org" <dev@dpdk.org>,
"Gobriel, Sameh" <sameh.gobriel@intel.com>, nd <nd@arm.com>
Subject: Re: [dpdk-dev] [PATCH v4 1/4] hash: fix race condition in iterate
Date: Tue, 2 Oct 2018 23:53:36 +0000 [thread overview]
Message-ID: <D2C4A16CA39F7F4E8E384D204491D7A6614EB05E@FMSMSX151.amr.corp.intel.com> (raw)
In-Reply-To: <AM6PR08MB3672168549D2B5DD5828B72F98E80@AM6PR08MB3672.eurprd08.prod.outlook.com>
>-----Original Message-----
>From: Honnappa Nagarahalli [mailto:Honnappa.Nagarahalli@arm.com]
>> >> /* Get position of entry in key table */
>> >> position = h->buckets[bucket_idx].key_idx[idx];
>> >If we change the while loop as I suggested as above, we can remove this line.
>> >
>> >> next_key = (struct rte_hash_key *) ((char *)h->key_store +
>>
>> [Wang, Yipeng] Sorry that I did not realize you already have it in your patch
>> set and I agree.
>> Do you want to export it as a bug fix in your patch set? I will remove my
>> change.
>Sure, I will make a separate commit for this.
[Wang, Yipeng] I fixed the issue you mentioned and put it in V5 and I saw you acked it. You don't need to change you patch now.
>>
>> For the lock free, do we need to protect it with version counter? Imagine the
>> following corner case:
>> While the iterator read the key and data, there is a writer deleted, removed,
>> and recycled the key-data pair, and write a new key and data into it. While the
>> writer are writing, will the reader reads out wrong key/data, or mismatched
>> key/data?
>>
>In the lock-free algorithm, the key-data is not 'freed' until the readers have completed all their references to the 'deleted' key-data.
>Hence, the writers will not be able to allocate the same key store index till the readers have stopped referring to the 'deleted' key-
>data.
>I re-checked my ladder diagrams [1] and I could not find any issues.
>
>[1] https://dpdkuserspace2018.sched.com/event/G44w/lock-free-read-write-concurrency-in-rtehash (PPT)
[Wang, Yipeng]
After checking your slides, I agree. It works with upper level application which should have RCU-like mechanisms to ensure
the grace period has finished before recycling. In this case, the logic is good!
If you haven't done so, could you be more specific in doc and the API comment to indicate that the key-data pair recycle function should only be called
after reader finished (or maybe specifically indicate RCU type of mechanism is needed?). I feel that users not familiar with this could easily
get it wrong.
Besides this, I don't have other concern.
next prev parent reply other threads:[~2018-10-02 23:57 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
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 [this message]
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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