From: "Morten Brørup" <mb@smartsharesystems.com>
To: "Stephen Hemminger" <stephen@networkplumber.org>,
"Mattias Rönnblom" <hofors@lysator.liu.se>
Cc: "Mattias Rönnblom" <mattias.ronnblom@ericsson.com>,
"Thomas Monjalon" <thomas@monjalon.net>,
"David Marchand" <david.marchand@redhat.com>,
dev@dpdk.org, onar.olsen@ericsson.com,
Honnappa.Nagarahalli@arm.com, nd@arm.com,
konstantin.ananyev@intel.com,
"Chengwen Feng" <fengchengwen@huawei.com>,
"Ola Liljedahl" <ola.liljedahl@arm.com>
Subject: RE: [PATCH v6] eal: add seqlock
Date: Mon, 9 May 2022 08:26:25 +0200 [thread overview]
Message-ID: <98CBD80474FA8B44BF855DF32C47DC35D8704D@smartserver.smartshare.dk> (raw)
In-Reply-To: <20220508204825.375965c8@hermes.local>
> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> Sent: Monday, 9 May 2022 05.48
>
> On Sun, 8 May 2022 21:40:58 +0200
> Mattias Rönnblom <hofors@lysator.liu.se> wrote:
>
> > > I think would be good to have the sequence count (read side only)
> like
> > > the kernel and sequence lock (sequence count + spinlock) as
> separate things.
> > >
> > > That way the application could use sequence count + ticket lock if
> it
> > > needed to scale to more writers.
> > >
If we want a seqlock based on a ticket lock, I would prefer that DPDK offers it, rather than requiring the application to implement it.
Regardless, adding the seqcount type as a separate thing could still make sense.
> >
> > Sounds reasonable. Would that be something like:
> >
> > typedef struct {
> > uint32_t sn;
> > } rte_seqlock_t;
> >
> > rte_seqlock_read_begin()
> > rte_seqlock_read_retry()
> > rte_seqlock_write_begin()
> > rte_seqlock_write_end()
> >
> > typedef struct {
> > rte_seqlock_t seqlock;
> > rte_spinlock_t wlock;
> > } rte_<something>_t;
> >
> > rte_<something>_read_begin()
> > rte_<something>_read_retry()
> > rte_<something>_write_lock()
> > rte_<something>_write_unlock()
> >
> > or are you suggesting removing the spinlock altogether, and leave
> > writer-side synchronization to the application (at least in this DPDK
> > release)?
>
>
> No, like Linux kernel. Use seqcount for the reader counter only object
> and seqlock for the seqcount + spinlock version.
In other words: Keep the existing names, i.e. rte_seqlock_t/rte_seqlock_functions(), for what you have already implemented, and use the names rte_seqcount_t/rte_seqcount_functions() for the variant without the lock.
Linux source code here:
https://elixir.bootlin.com/linux/v5.10.113/source/include/linux/seqlock.h
I suppose that the rte_seqcount_t primitive should go into a separate file; it is not really a lock.
next prev parent reply other threads:[~2022-05-09 6:26 UTC|newest]
Thread overview: 104+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-22 16:10 DPDK seqlock Mattias Rönnblom
2022-03-22 16:46 ` Ananyev, Konstantin
2022-03-24 4:52 ` Honnappa Nagarahalli
2022-03-24 5:06 ` Stephen Hemminger
2022-03-24 11:34 ` Mattias Rönnblom
2022-03-25 20:24 ` [RFC] eal: add seqlock Mattias Rönnblom
2022-03-25 21:10 ` Stephen Hemminger
2022-03-26 14:57 ` Mattias Rönnblom
2022-03-27 14:49 ` Ananyev, Konstantin
2022-03-27 17:42 ` Mattias Rönnblom
2022-03-28 10:53 ` Ananyev, Konstantin
2022-03-28 14:06 ` Ola Liljedahl
2022-03-29 8:32 ` Mattias Rönnblom
2022-03-29 13:20 ` Ananyev, Konstantin
2022-03-30 10:07 ` [PATCH] " Mattias Rönnblom
2022-03-30 10:50 ` Morten Brørup
2022-03-30 11:24 ` Tyler Retzlaff
2022-03-30 11:25 ` Mattias Rönnblom
2022-03-30 14:26 ` [PATCH v2] " Mattias Rönnblom
2022-03-31 7:46 ` Mattias Rönnblom
2022-03-31 9:04 ` Ola Liljedahl
2022-03-31 9:25 ` Morten Brørup
2022-03-31 9:38 ` Ola Liljedahl
2022-03-31 10:03 ` Morten Brørup
2022-03-31 11:44 ` Ola Liljedahl
2022-03-31 11:50 ` Morten Brørup
2022-03-31 14:02 ` Mattias Rönnblom
2022-04-01 15:07 ` [PATCH v3] " Mattias Rönnblom
2022-04-02 0:21 ` Honnappa Nagarahalli
2022-04-02 11:01 ` Morten Brørup
2022-04-02 19:38 ` Honnappa Nagarahalli
2022-04-10 13:51 ` [RFC 1/3] eal: add macro to warn for unused function return values Mattias Rönnblom
2022-04-10 13:51 ` [RFC 2/3] eal: emit warning for unused trylock return value Mattias Rönnblom
2022-04-10 13:51 ` [RFC 3/3] examples/bond: fix invalid use of trylock Mattias Rönnblom
2022-04-11 1:01 ` Min Hu (Connor)
2022-04-11 14:32 ` Mattias Rönnblom
2022-04-11 11:25 ` David Marchand
2022-04-11 14:33 ` Mattias Rönnblom
2022-04-10 18:02 ` [RFC 1/3] eal: add macro to warn for unused function return values Stephen Hemminger
2022-04-10 18:50 ` Mattias Rönnblom
2022-04-11 7:17 ` Morten Brørup
2022-04-11 14:29 ` Mattias Rönnblom
2022-04-11 9:16 ` Bruce Richardson
2022-04-11 14:27 ` Mattias Rönnblom
2022-04-11 15:15 ` [PATCH " Mattias Rönnblom
2022-04-11 15:15 ` [PATCH 2/3] eal: emit warning for unused trylock return value Mattias Rönnblom
2022-04-11 15:29 ` Morten Brørup
2022-04-11 15:15 ` [PATCH 3/3] examples/bond: fix invalid use of trylock Mattias Rönnblom
2022-04-14 12:06 ` David Marchand
2022-04-11 15:25 ` [PATCH 1/3] eal: add macro to warn for unused function return values Morten Brørup
2022-04-11 18:24 ` [RFC " Tyler Retzlaff
2022-04-03 6:10 ` [PATCH v3] eal: add seqlock Mattias Rönnblom
2022-04-03 17:27 ` Honnappa Nagarahalli
2022-04-03 18:37 ` Ola Liljedahl
2022-04-04 21:56 ` Honnappa Nagarahalli
2022-04-03 6:33 ` Mattias Rönnblom
2022-04-03 17:37 ` Honnappa Nagarahalli
2022-04-08 13:45 ` Mattias Rönnblom
2022-04-02 18:15 ` Ola Liljedahl
2022-04-02 19:31 ` Honnappa Nagarahalli
2022-04-02 20:36 ` Morten Brørup
2022-04-02 22:01 ` Honnappa Nagarahalli
2022-04-03 18:11 ` Ola Liljedahl
2022-04-03 6:51 ` Mattias Rönnblom
2022-03-31 13:51 ` [PATCH v2] " Mattias Rönnblom
2022-04-02 0:54 ` Stephen Hemminger
2022-04-02 10:25 ` Morten Brørup
2022-04-02 17:43 ` Ola Liljedahl
2022-03-31 13:38 ` Mattias Rönnblom
2022-03-31 14:53 ` Ola Liljedahl
2022-04-02 0:52 ` Stephen Hemminger
2022-04-03 6:23 ` Mattias Rönnblom
2022-04-02 0:50 ` Stephen Hemminger
2022-04-02 17:54 ` Ola Liljedahl
2022-04-02 19:37 ` Honnappa Nagarahalli
2022-04-05 20:16 ` Stephen Hemminger
2022-04-08 13:50 ` Mattias Rönnblom
2022-04-08 14:24 ` [PATCH v4] " Mattias Rönnblom
2022-04-08 15:17 ` Stephen Hemminger
2022-04-08 16:24 ` Mattias Rönnblom
2022-04-08 15:19 ` Stephen Hemminger
2022-04-08 16:37 ` Mattias Rönnblom
2022-04-08 16:48 ` Mattias Rönnblom
2022-04-12 17:27 ` Ananyev, Konstantin
2022-04-28 10:28 ` David Marchand
2022-05-01 13:46 ` Mattias Rönnblom
2022-05-01 14:03 ` [PATCH v5] " Mattias Rönnblom
2022-05-01 14:22 ` Mattias Rönnblom
2022-05-02 6:47 ` David Marchand
2022-05-01 20:17 ` Stephen Hemminger
2022-05-02 4:51 ` Mattias Rönnblom
2022-05-06 1:26 ` fengchengwen
2022-05-06 1:33 ` Honnappa Nagarahalli
2022-05-06 4:17 ` fengchengwen
2022-05-06 5:19 ` Honnappa Nagarahalli
2022-05-06 7:03 ` fengchengwen
2022-05-08 11:56 ` Mattias Rönnblom
2022-05-08 12:12 ` [PATCH v6] " Mattias Rönnblom
2022-05-08 16:10 ` Stephen Hemminger
2022-05-08 19:40 ` Mattias Rönnblom
2022-05-09 3:48 ` Stephen Hemminger
2022-05-09 6:26 ` Morten Brørup [this message]
2022-05-13 6:27 ` Mattias Rönnblom
2022-03-23 12:04 ` DPDK seqlock Morten Brørup
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