From: "Mattias Rönnblom" <hofors@lysator.liu.se>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: "Ferruh Yigit" <ferruh.yigit@amd.com>,
"John W. Linville" <linville@tuxdriver.com>,
"Thomas Monjalon" <thomas@monjalon.net>,
dev@dpdk.org, "Mattias Rönnblom" <mattias.ronnblom@ericsson.com>,
"Morten Brørup" <mb@smartsharesystems.com>
Subject: Re: [RFC v2] net/af_packet: make stats reset reliable
Date: Thu, 2 May 2024 23:26:31 +0200 [thread overview]
Message-ID: <e3e6929b-f9b9-439d-8e50-faf161992154@lysator.liu.se> (raw)
In-Reply-To: <20240502112602.27d55fb8@hermes.local>
On 2024-05-02 20:26, Stephen Hemminger wrote:
> On Thu, 2 May 2024 19:37:28 +0200
> Mattias Rönnblom <hofors@lysator.liu.se> wrote:
>
>>>
>>> Do we need to declare count as '_Atomic', I wasn't planning to make
>>> variable _Atomic. This way assignment won't introduce any memory barrier.
>>>
>>
>> To use atomics in DPDK, the current requirements seems to be to use
>> RTE_ATOMIC(). That macro expands to _Atomic in enable_stdatomic=true
>> builds, and nothing otherwise.
>>
>> Carefully crafted code using atomics will achieved the same performance
>> and be more correct than the non-atomic variant. However, in practice, I
>> think the non-atomic variant is very likely to produce the desired results.
>
> You are confusing atomic usage for thread safety, with the necessity
> of compiler barriers.
>
Are you suggesting that program-level C11 atomic stores risk being
delayed, indefinitely? I could only find a draft version of the
standard, but there 7.17.3 says "Implementations should make atomic
stores visible to atomic loads within a reasonable amount of time."
An atomic relaxed store will be much cheaper than a compiler barrier.
> Stats should not be volatile.
Sure, and I also don't think compiler barriers should be needed.
next prev parent reply other threads:[~2024-05-02 21:26 UTC|newest]
Thread overview: 178+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-25 17:46 [RFC] " Ferruh Yigit
2024-04-26 11:33 ` Morten Brørup
2024-04-26 13:37 ` Ferruh Yigit
2024-04-26 14:56 ` Morten Brørup
2024-04-28 15:42 ` Mattias Rönnblom
2024-04-26 14:38 ` [RFC v2] " Ferruh Yigit
2024-04-26 14:47 ` Morten Brørup
2024-04-28 15:11 ` Mattias Rönnblom
2024-05-01 16:19 ` Ferruh Yigit
2024-05-02 5:51 ` Mattias Rönnblom
2024-05-02 14:22 ` Ferruh Yigit
2024-05-02 15:59 ` Stephen Hemminger
2024-05-02 18:20 ` Ferruh Yigit
2024-05-02 17:37 ` Mattias Rönnblom
2024-05-02 18:26 ` Stephen Hemminger
2024-05-02 21:26 ` Mattias Rönnblom [this message]
2024-05-02 21:46 ` Stephen Hemminger
2024-05-07 7:23 ` Mattias Rönnblom
2024-05-07 13:49 ` Ferruh Yigit
2024-05-07 14:51 ` Stephen Hemminger
2024-05-07 16:00 ` Morten Brørup
2024-05-07 16:54 ` Ferruh Yigit
2024-05-07 18:47 ` Stephen Hemminger
2024-05-08 7:48 ` Mattias Rönnblom
2024-05-08 6:28 ` Mattias Rönnblom
2024-05-08 6:25 ` Mattias Rönnblom
2024-05-07 19:19 ` Morten Brørup
2024-05-08 6:34 ` Mattias Rönnblom
2024-05-08 7:10 ` Morten Brørup
2024-05-08 7:23 ` Mattias Rönnblom
2024-04-26 21:28 ` [RFC] " Patrick Robb
2024-05-03 15:45 ` [RFC v3] " Ferruh Yigit
2024-05-03 22:00 ` Stephen Hemminger
2024-05-07 13:48 ` Ferruh Yigit
2024-05-07 14:52 ` Stephen Hemminger
2024-05-07 17:27 ` Ferruh Yigit
2024-05-08 7:19 ` Mattias Rönnblom
2024-05-08 15:23 ` Stephen Hemminger
2024-05-08 19:48 ` Ferruh Yigit
2024-05-08 20:54 ` Stephen Hemminger
2024-05-09 7:43 ` Morten Brørup
2024-05-09 9:29 ` Bruce Richardson
2024-05-09 11:37 ` Morten Brørup
2024-05-09 14:19 ` Morten Brørup
2024-05-10 4:56 ` Stephen Hemminger
2024-05-10 9:14 ` Morten Brørup
2024-05-26 7:10 ` Mattias Rönnblom
2024-05-26 7:07 ` Mattias Rönnblom
2024-05-26 7:03 ` Mattias Rönnblom
2024-05-26 7:21 ` Mattias Rönnblom
2024-05-07 15:27 ` Morten Brørup
2024-05-07 17:40 ` Ferruh Yigit
2024-05-10 5:01 ` [RFC 0/3] generic sw counters Stephen Hemminger
2024-05-10 5:01 ` [RFC 1/3] ethdev: add internal helper of SW driver statistics Stephen Hemminger
2024-05-10 5:01 ` [RFC 2/3] net/af_packet: use SW stats helper Stephen Hemminger
2024-05-10 5:01 ` [RFC 3/3] net/tap: use generic SW stats Stephen Hemminger
2024-05-10 17:29 ` [RFC 0/3] generic sw counters Morten Brørup
2024-05-10 19:30 ` Stephen Hemminger
2024-05-13 18:52 ` [RFC v2 0/7] generic SW counters Stephen Hemminger
2024-05-13 18:52 ` [RFC v2 1/7] eal: generic 64 bit counter Stephen Hemminger
2024-05-13 19:36 ` Morten Brørup
2024-05-13 18:52 ` [RFC v2 2/7] ethdev: add internal helper of SW driver statistics Stephen Hemminger
2024-05-13 18:52 ` [RFC v2 3/7] net/af_packet: use SW stats helper Stephen Hemminger
2024-05-13 18:52 ` [RFC v2 4/7] net/tap: use generic SW stats Stephen Hemminger
2024-05-13 18:52 ` [RFC v2 5/7] net/pcap: " Stephen Hemminger
2024-05-13 18:52 ` [RFC v2 6/7] net/af_xdp: " Stephen Hemminger
2024-05-13 18:52 ` [RFC v2 7/7] net/ring: " Stephen Hemminger
2024-05-14 15:35 ` [PATCH v3 0/7] Generic SW counters Stephen Hemminger
2024-05-14 15:35 ` [PATCH v3 1/7] eal: generic 64 bit counter Stephen Hemminger
2024-05-15 9:30 ` Morten Brørup
2024-05-15 15:03 ` Stephen Hemminger
2024-05-15 16:18 ` Morten Brørup
2024-05-26 7:34 ` Mattias Rönnblom
2024-05-26 6:45 ` Mattias Rönnblom
2024-05-14 15:35 ` [PATCH v3 2/7] ethdev: add internal helper of SW driver statistics Stephen Hemminger
2024-05-14 15:35 ` [PATCH v3 3/7] net/af_packet: use SW stats helper Stephen Hemminger
2024-05-14 15:35 ` [PATCH v3 4/7] net/af_xdp: use generic SW stats Stephen Hemminger
2024-05-14 15:35 ` [PATCH v3 5/7] net/pcap: " Stephen Hemminger
2024-05-14 15:35 ` [PATCH v3 6/7] net/ring: " Stephen Hemminger
2024-05-14 15:35 ` [PATCH v3 7/7] net/tap: " Stephen Hemminger
2024-05-15 23:40 ` [PATCH v4 0/8] Generic 64 bit counters for SW PMD's Stephen Hemminger
2024-05-15 23:40 ` [PATCH v4 1/8] eal: generic 64 bit counter Stephen Hemminger
2024-05-15 23:40 ` [PATCH v4 2/8] ethdev: add common counters for statistics Stephen Hemminger
2024-05-15 23:40 ` [PATCH v4 3/8] net/af_packet: use generic SW stats Stephen Hemminger
2024-05-15 23:40 ` [PATCH v4 4/8] net/af_xdp: " Stephen Hemminger
2024-05-15 23:40 ` [PATCH v4 5/8] net/pcap: " Stephen Hemminger
2024-05-15 23:40 ` [PATCH v4 6/8] net/ring: " Stephen Hemminger
2024-05-15 23:40 ` [PATCH v4 7/8] net/tap: " Stephen Hemminger
2024-05-15 23:41 ` [PATCH v4 8/8] net/null: " Stephen Hemminger
2024-05-16 15:40 ` [PATCH v5 0/9] Generic 64 bit counters Stephen Hemminger
2024-05-16 15:40 ` [PATCH v5 1/9] eal: generic 64 bit counter Stephen Hemminger
2024-05-16 18:22 ` Wathsala Wathawana Vithanage
2024-05-16 21:42 ` Stephen Hemminger
2024-05-17 2:39 ` Honnappa Nagarahalli
2024-05-17 3:29 ` Stephen Hemminger
2024-05-17 4:39 ` Honnappa Nagarahalli
2024-05-16 15:40 ` [PATCH v5 2/9] ethdev: add common counters for statistics Stephen Hemminger
2024-05-16 18:30 ` Wathsala Wathawana Vithanage
2024-05-17 0:19 ` Stephen Hemminger
2024-05-16 15:40 ` [PATCH v5 3/9] net/af_packet: use generic SW stats Stephen Hemminger
2024-05-16 15:40 ` [PATCH v5 4/9] net/af_xdp: " Stephen Hemminger
2024-05-16 15:40 ` [PATCH v5 5/9] net/pcap: " Stephen Hemminger
2024-05-16 15:40 ` [PATCH v5 6/9] test/pmd_ring: initialize mbufs Stephen Hemminger
2024-05-16 15:40 ` [PATCH v5 7/9] net/ring: use generic SW stats Stephen Hemminger
2024-05-16 15:40 ` [PATCH v5 8/9] net/tap: " Stephen Hemminger
2024-05-16 15:40 ` [PATCH v5 9/9] net/null: " Stephen Hemminger
2024-05-17 0:12 ` [PATCH v6 0/9] Generic 64 bit counters for SW drivers Stephen Hemminger
2024-05-17 0:12 ` [PATCH v6 1/9] eal: generic 64 bit counter Stephen Hemminger
2024-05-17 2:45 ` Honnappa Nagarahalli
2024-05-17 3:30 ` Stephen Hemminger
2024-05-17 4:26 ` Honnappa Nagarahalli
2024-05-17 6:44 ` Morten Brørup
2024-05-17 15:05 ` Stephen Hemminger
2024-05-17 16:18 ` Stephen Hemminger
2024-05-18 14:00 ` Morten Brørup
2024-05-19 15:13 ` Stephen Hemminger
2024-05-19 17:10 ` Morten Brørup
2024-05-19 22:49 ` Stephen Hemminger
2024-05-20 7:57 ` Morten Brørup
2024-05-17 15:07 ` Stephen Hemminger
2024-05-17 0:12 ` [PATCH v6 2/9] ethdev: add common counters for statistics Stephen Hemminger
2024-05-17 0:12 ` [PATCH v6 3/9] net/af_packet: use generic SW stats Stephen Hemminger
2024-05-17 0:12 ` [PATCH v6 4/9] net/af_xdp: " Stephen Hemminger
2024-05-17 13:34 ` Loftus, Ciara
2024-05-17 14:54 ` Stephen Hemminger
2024-05-17 0:12 ` [PATCH v6 5/9] net/pcap: " Stephen Hemminger
2024-05-17 0:12 ` [PATCH v6 6/9] test/pmd_ring: initialize mbufs Stephen Hemminger
2024-05-17 0:12 ` [PATCH v6 7/9] net/ring: use generic SW stats Stephen Hemminger
2024-05-17 0:12 ` [PATCH v6 8/9] net/tap: " Stephen Hemminger
2024-05-17 0:12 ` [PATCH v6 9/9] net/null: " Stephen Hemminger
2024-05-17 17:35 ` [PATCH v7 0/9] Use weak atomic operations for SW PMD counters Stephen Hemminger
2024-05-17 17:35 ` [PATCH v7 1/9] eal: generic 64 bit counter Stephen Hemminger
2024-05-17 17:35 ` [PATCH v7 2/9] ethdev: add common counters for statistics Stephen Hemminger
2024-05-17 17:35 ` [PATCH v7 3/9] net/af_packet: use generic SW stats Stephen Hemminger
2024-05-17 17:35 ` [PATCH v7 4/9] net/af_xdp: " Stephen Hemminger
2024-05-17 17:35 ` [PATCH v7 5/9] net/pcap: " Stephen Hemminger
2024-05-17 17:35 ` [PATCH v7 6/9] test/pmd_ring: initialize mbufs Stephen Hemminger
2024-05-17 17:35 ` [PATCH v7 7/9] net/ring: use generic SW stats Stephen Hemminger
2024-05-17 17:35 ` [PATCH v7 8/9] net/tap: " Stephen Hemminger
2024-05-17 17:35 ` [PATCH v7 9/9] net/null: " Stephen Hemminger
2024-05-21 17:00 ` [PATCH v8 0/8] Common statistics routines for SW based PMD's Stephen Hemminger
2024-05-21 17:00 ` [PATCH v8 1/8] eal: generic 64 bit counter Stephen Hemminger
2024-05-21 17:00 ` [PATCH v8 2/8] ethdev: add common counters for statistics Stephen Hemminger
2024-05-21 17:00 ` [PATCH v8 3/8] net/af_packet: use generic SW stats Stephen Hemminger
2024-05-21 17:00 ` [PATCH v8 4/8] net/af_xdp: " Stephen Hemminger
2024-05-21 17:00 ` [PATCH v8 5/8] net/pcap: " Stephen Hemminger
2024-05-21 17:00 ` [PATCH v8 6/8] net/ring: " Stephen Hemminger
2024-05-21 17:00 ` [PATCH v8 7/8] net/tap: " Stephen Hemminger
2024-05-21 17:00 ` [PATCH v8 8/8] net/null: " Stephen Hemminger
2024-05-21 20:16 ` [PATCH v9 0/8] Common statistics for SW PMD's Stephen Hemminger
2024-05-21 20:16 ` [PATCH v9 1/8] eal: generic 64 bit counter Stephen Hemminger
2024-05-22 8:31 ` Morten Brørup
2024-05-22 15:33 ` Stephen Hemminger
2024-05-22 18:09 ` Morten Brørup
2024-05-22 19:53 ` Stephen Hemminger
2024-05-22 20:56 ` Morten Brørup
2024-05-22 15:37 ` Stephen Hemminger
2024-05-22 17:57 ` Morten Brørup
2024-05-22 19:01 ` Tyler Retzlaff
2024-05-22 19:51 ` Stephen Hemminger
2024-05-26 14:46 ` Mattias Rönnblom
2024-05-26 14:39 ` Mattias Rönnblom
2024-05-21 20:16 ` [PATCH v9 2/8] ethdev: add common counters for statistics Stephen Hemminger
2024-05-21 20:16 ` [PATCH v9 3/8] net/af_packet: use generic SW stats Stephen Hemminger
2024-05-21 20:16 ` [PATCH v9 4/8] net/af_xdp: " Stephen Hemminger
2024-05-21 20:16 ` [PATCH v9 5/8] net/pcap: " Stephen Hemminger
2024-05-21 20:16 ` [PATCH v9 6/8] net/ring: " Stephen Hemminger
2024-05-21 20:16 ` [PATCH v9 7/8] net/tap: " Stephen Hemminger
2024-05-21 20:16 ` [PATCH v9 8/8] net/null: " Stephen Hemminger
2024-05-22 16:12 ` [PATCH v10 0/8] Common statistics for software PMD's Stephen Hemminger
2024-05-22 16:12 ` [PATCH v10 1/8] eal: generic 64 bit counter Stephen Hemminger
2024-05-22 16:12 ` [PATCH v10 2/8] ethdev: add common counters for statistics Stephen Hemminger
2024-05-22 16:12 ` [PATCH v10 3/8] net/af_packet: use generic SW stats Stephen Hemminger
2024-05-22 16:12 ` [PATCH v10 4/8] net/af_xdp: " Stephen Hemminger
2024-05-22 16:12 ` [PATCH v10 5/8] net/pcap: " Stephen Hemminger
2024-05-22 16:12 ` [PATCH v10 6/8] net/ring: " Stephen Hemminger
2024-05-22 16:12 ` [PATCH v10 7/8] net/tap: " Stephen Hemminger
2024-05-22 16:12 ` [PATCH v10 8/8] net/null: " Stephen Hemminger
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