From: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
To: mattias.ronnblom <mattias.ronnblom@ericsson.com>,
"dev@dpdk.org" <dev@dpdk.org>
Cc: Thomas Monjalon <thomas@monjalon.net>,
David Marchand <david.marchand@redhat.com>,
"Olsen, Onar" <onar.olsen@ericsson.com>,
"Honnappa.Nagarahalli@arm.com" <Honnappa.Nagarahalli@arm.com>,
"nd@arm.com" <nd@arm.com>,
"mb@smartsharesystems.com" <mb@smartsharesystems.com>,
"stephen@networkplumber.org" <stephen@networkplumber.org>,
mattias.ronnblom <mattias.ronnblom@ericsson.com>,
Ola Liljedahl <ola.liljedahl@arm.com>
Subject: RE: [RFC] eal: add seqlock
Date: Sun, 27 Mar 2022 14:49:02 +0000 [thread overview]
Message-ID: <DM6PR11MB44916E6635D263B2B3A6D8B29A1C9@DM6PR11MB4491.namprd11.prod.outlook.com> (raw)
In-Reply-To: <20220325202428.94628-1-mattias.ronnblom@ericsson.com>
> diff --git a/lib/eal/include/meson.build b/lib/eal/include/meson.build
> index 9700494816..48df5f1a21 100644
> --- a/lib/eal/include/meson.build
> +++ b/lib/eal/include/meson.build
> @@ -36,6 +36,7 @@ headers += files(
> 'rte_per_lcore.h',
> 'rte_random.h',
> 'rte_reciprocal.h',
> + 'rte_seqlock.h',
> 'rte_service.h',
> 'rte_service_component.h',
> 'rte_string_fns.h',
> diff --git a/lib/eal/include/rte_seqlock.h b/lib/eal/include/rte_seqlock.h
> new file mode 100644
> index 0000000000..b975ca848a
> --- /dev/null
> +++ b/lib/eal/include/rte_seqlock.h
> @@ -0,0 +1,84 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2022 Ericsson AB
> + */
> +
> +#ifndef _RTE_SEQLOCK_H_
> +#define _RTE_SEQLOCK_H_
> +
> +#include <stdbool.h>
> +#include <stdint.h>
> +
> +#include <rte_atomic.h>
> +#include <rte_branch_prediction.h>
> +#include <rte_spinlock.h>
> +
> +struct rte_seqlock {
> + uint64_t sn;
> + rte_spinlock_t lock;
> +};
> +
> +typedef struct rte_seqlock rte_seqlock_t;
> +
> +__rte_experimental
> +void
> +rte_seqlock_init(rte_seqlock_t *seqlock);
Probably worth to have static initializer too.
> +
> +__rte_experimental
> +static inline uint64_t
> +rte_seqlock_read_begin(const rte_seqlock_t *seqlock)
> +{
> + /* __ATOMIC_ACQUIRE to prevent loads after (in program order)
> + * from happening before the sn load. Syncronizes-with the
> + * store release in rte_seqlock_end().
> + */
> + return __atomic_load_n(&seqlock->sn, __ATOMIC_ACQUIRE);
> +}
> +
> +__rte_experimental
> +static inline bool
> +rte_seqlock_read_retry(const rte_seqlock_t *seqlock, uint64_t begin_sn)
> +{
> + uint64_t end_sn;
> +
> + /* make sure the data loads happens before the sn load */
> + rte_atomic_thread_fence(__ATOMIC_ACQUIRE);
That's sort of 'read_end' correct?
If so, shouldn't it be '__ATOMIC_RELEASE' instead here,
and
end_sn = __atomic_load_n(..., (__ATOMIC_ACQUIRE)
on the line below?
> +
> + end_sn = __atomic_load_n(&seqlock->sn, __ATOMIC_RELAXED);
> +
> + return unlikely(begin_sn & 1 || begin_sn != end_sn);
> +}
> +
> +__rte_experimental
> +static inline void
> +rte_seqlock_write_begin(rte_seqlock_t *seqlock)
> +{
> + uint64_t sn;
> +
> + /* to synchronize with other writers */
> + rte_spinlock_lock(&seqlock->lock);
> +
> + sn = seqlock->sn + 1;
> +
> + __atomic_store_n(&seqlock->sn, sn, __ATOMIC_RELAXED);
> +
> + /* __ATOMIC_RELEASE to prevent stores after (in program order)
> + * from happening before the sn store.
> + */
> + rte_atomic_thread_fence(__ATOMIC_RELEASE);
I think it needs to be '__ATOMIC_ACQUIRE' here instead of '__ATOMIC_RELEASE'.
> +}
> +
> +__rte_experimental
> +static inline void
> +rte_seqlock_write_end(rte_seqlock_t *seqlock)
> +{
> + uint64_t sn;
> +
> + sn = seqlock->sn + 1;
> +
> + /* synchronizes-with the load acquire in rte_seqlock_begin() */
> + __atomic_store_n(&seqlock->sn, sn, __ATOMIC_RELEASE);
> +
> + rte_spinlock_unlock(&seqlock->lock);
> +}
> +
next prev parent reply other threads:[~2022-03-27 14:49 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 [this message]
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
2022-05-13 6:27 ` Mattias Rönnblom
2022-03-23 12:04 ` DPDK seqlock Morten Brørup
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