From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by dpdk.org (Postfix) with ESMTP id 2A07B2BAC for ; Wed, 6 Mar 2019 16:04:09 +0100 (CET) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 06 Mar 2019 07:04:06 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.58,448,1544515200"; d="scan'208";a="139634859" Received: from txasoft-yocto.an.intel.com ([10.123.72.192]) by orsmga002.jf.intel.com with ESMTP; 06 Mar 2019 07:04:04 -0800 From: Gage Eads To: dev@dpdk.org Cc: olivier.matz@6wind.com, arybchenko@solarflare.com, bruce.richardson@intel.com, konstantin.ananyev@intel.com, stephen@networkplumber.org, jerinj@marvell.com, mczekaj@marvell.com, nd@arm.com, Ola.Liljedahl@arm.com Date: Wed, 6 Mar 2019 09:03:36 -0600 Message-Id: <20190306150342.2894-1-gage.eads@intel.com> X-Mailer: git-send-email 2.13.6 In-Reply-To: <20190305174019.9693-1-gage.eads@intel.com> References: <20190305174019.9693-1-gage.eads@intel.com> Subject: [dpdk-dev] [PATCH v6 0/6] Add lock-free ring and mempool handler X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 06 Mar 2019 15:04:09 -0000 For some users, the rte ring's "non-preemptive" constraint is not acceptable; for example, if the application uses a mixture of pinned high-priority threads and multiplexed low-priority threads that share a mempool. This patchset introduces a lock-free ring and a mempool based on it. The lock-free algorithm relies on a double-pointer compare-and-swap, so for 64-bit architectures it is currently limited to x86_64. The ring uses more compare-and-swap atomic operations than the regular rte ring: With no contention, an enqueue of n pointers uses (1 + n) CAS operations and a dequeue of n pointers uses 1. This algorithm has worse average-case performance than the regular rte ring (particularly a highly-contended ring with large bulk accesses), however: - For applications with preemptible pthreads, the regular rte ring's worst-case performance (i.e. one thread being preempted in the update_tail() critical section) is much worse than the lock-free ring's. - Software caching can mitigate the average case performance for ring-based algorithms. For example, a lock-free ring based mempool (a likely use case for this ring) with per-thread caching. The lock-free ring is enabled via a new flag, RING_F_LF. For ease-of-use, existing ring enqueue/dequeue functions work with both standard and lock-free rings. This is also an experimental API, so RING_F_LF users must build with the ALLOW_EXPERIMENTAL_API flag. This patchset also adds lock-free versions of ring_autotest and ring_perf_autotest, and a lock-free ring based mempool. This patchset makes one API change; a deprecation notice was posted in a separate commit[1]. This patchset depends on the 128-bit compare-and-set patch[2]. [1] http://mails.dpdk.org/archives/dev/2019-February/124321.html [2] http://mails.dpdk.org/archives/dev/2019-March/125751.html v6: - Rebase patchset onto master (test/test/ -> app/test/) v5: - Incorporated lfring's enqueue and dequeue logic from http://mails.dpdk.org/archives/dev/2019-January/124242.html - Renamed non-blocking -> lock-free and NB -> LF to align with a similar change in the lock-free stack patchset: http://mails.dpdk.org/archives/dev/2019-March/125797.html - Added support for 32-bit architectures by using the full 32b of the modification counter and requiring LF rings on these architectures to be at least 1024 entries. - Updated to the latest rte_atomic128_cmp_exchange() interface. - Added ring start marker to struct rte_ring v4: - Split out nb_enqueue and nb_dequeue functions in generic and C11 versions, with the necessary memory ordering behavior for weakly consistent machines. - Convert size_t variables (from v2) to uint64_t and no-longer-applicable comment about variably-sized ring indexes. - Fix bug in nb_enqueue_mp that the breaks the non-blocking guarantee. - Split the ring_ptr cast into two lines. - Change the dependent patchset from the non-blocking stack patch series to one only containing the 128b CAS commit v3: - Avoid the ABI break by putting 64-bit head and tail values in the same cacheline as struct rte_ring's prod and cons members. - Don't attempt to compile rte_atomic128_cmpset without ALLOW_EXPERIMENTAL_API, as this would break a large number of libraries. - Add a helpful warning to __rte_ring_do_nb_enqueue_mp() in case someone tries to use RING_F_NB without the ALLOW_EXPERIMENTAL_API flag. - Update the ring mempool to use experimental APIs - Clarify that RINB_F_NB is only limited to x86_64 currently; e.g. ARMv8 has the ISA support for 128-bit CAS to eventually support it. v2: - Merge separate docs commit into patch #5 - Convert uintptr_t to size_t - Add a compile-time check for the size of size_t - Fix a space-after-typecast issue - Fix an unnecessary-parentheses checkpatch warning - Bump librte_ring's library version Gage Eads (6): ring: add a pointer-width headtail structure ring: add a ring start marker ring: add a lock-free implementation test_ring: add lock-free ring autotest test_ring_perf: add lock-free ring perf test mempool/ring: add lock-free ring handlers app/test/test_ring.c | 61 +-- app/test/test_ring_perf.c | 19 +- doc/guides/prog_guide/env_abstraction_layer.rst | 10 + drivers/mempool/ring/Makefile | 1 + drivers/mempool/ring/meson.build | 2 + drivers/mempool/ring/rte_mempool_ring.c | 58 ++- lib/librte_ring/rte_ring.c | 92 ++++- lib/librte_ring/rte_ring.h | 334 ++++++++++++++-- lib/librte_ring/rte_ring_c11_mem.h | 501 ++++++++++++++++++++++++ lib/librte_ring/rte_ring_generic.h | 484 +++++++++++++++++++++++ lib/librte_ring/rte_ring_version.map | 7 + 11 files changed, 1492 insertions(+), 77 deletions(-) -- 2.13.6