From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id 7608CA058A; Fri, 17 Apr 2020 15:36:53 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id C89211E895; Fri, 17 Apr 2020 15:36:51 +0200 (CEST) Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by dpdk.org (Postfix) with ESMTP id 03C881E886 for ; Fri, 17 Apr 2020 15:36:49 +0200 (CEST) IronPort-SDR: 4Ex/a7CJwTZnJh2dkcZkyHMTJXWJ2ZH7JbB5JHo6PcwjyaTQ+cBzW9F49F0NYy7xHwxiRLATzH TuMFvRgvW6uA== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Apr 2020 06:36:49 -0700 IronPort-SDR: +yH/9MW5umymHj+xzHyiIN7GSY2WLpLZrJ9nPICpyWbwcXcUbgSqofaDAXHs13IuFLmHYtC6mi sqoddYvreOGA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,395,1580803200"; d="scan'208";a="254209863" Received: from sivswdev08.ir.intel.com ([10.237.217.47]) by orsmga003.jf.intel.com with ESMTP; 17 Apr 2020 06:36:47 -0700 From: Konstantin Ananyev To: dev@dpdk.org Cc: honnappa.nagarahalli@arm.com, david.marchand@redhat.com, jielong.zjl@antfin.com, Konstantin Ananyev Date: Fri, 17 Apr 2020 14:36:30 +0100 Message-Id: <20200417133639.14019-1-konstantin.ananyev@intel.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20200403174235.23308-1-konstantin.ananyev@intel.com> References: <20200403174235.23308-1-konstantin.ananyev@intel.com> Subject: [dpdk-dev] [PATCH v4 0/9] New sync modes for ring 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: , Errors-To: dev-bounces@dpdk.org Sender: "dev" V3 - V4 changes: Address comments from Honnappa: 1. for new sync modes make legacy API wrappers around _elem_ calls 2. remove rte_ring_(hts|rts)_generic.h 3. few changes in C11 version 4. peek API - add missing functions for _elem_ 5. remove _IS_SP/_IS_MP, etc. internal macros 6. fix param types (obj_table) for _elem_functions 7. fix formal API comments 8. deduplicate code for test_ring_stress 9. added functional tests for new sync modes V2 - V3 changes: 1. Few more compilation fixes (for gcc 4.8.X) 2. Extra update devtools/libabigail.abignore (workaround) V1 - V2 changes: 1. Fix compilation issues 2. Add C11 atomics support 3. Updates devtools/libabigail.abignore (workaround) RFC - V1 changes: 1. remove ABI brekage (at least I hope I did) 2. Add support for ring_elem 3. Rework peek related API a bit 4. Rework test to make it less verbose and unite all test-cases in one command 5. Add new test-case for MT peek API TODO list: 1. Update docs These days more and more customers use(/try to use) DPDK based apps within overcommitted systems (multiple acttive threads over same pysical cores): VM, container deployments, etc. One quite common problem they hit: Lock-Holder-Preemption/Lock-Waiter-Preemption with rte_ring. LHP is quite a common problem for spin-based sync primitives (spin-locks, etc.) on overcommitted systems. The situation gets much worse when some sort of fair-locking technique is used (ticket-lock, etc.). As now not only lock-owner but also lock-waiters scheduling order matters a lot (LWP). These two problems are well-known for kernel within VMs: http://www-archive.xenproject.org/files/xensummitboston08/LHP.pdf https://www.cs.hs-rm.de/~kaiser/events/wamos2017/Slides/selcuk.pdf The problem with rte_ring is that while head accusion is sort of un-fair locking, waiting on tail is very similar to ticket lock schema - tail has to be updated in particular order. That makes current rte_ring implementation to perform really pure on some overcommited scenarios. It is probably not possible to completely resolve LHP problem in userspace only (without some kernel communication/intervention). But removing fairness at tail update helps to avoid LWP and can mitigate the situation significantly. This patch proposes two new optional ring synchronization modes: 1) Head/Tail Sync (HTS) mode In that mode enqueue/dequeue operation is fully serialized: only one thread at a time is allowed to perform given op. As another enhancement provide ability to split enqueue/dequeue operation into two phases: - enqueue/dequeue start - enqueue/dequeue finish That allows user to inspect objects in the ring without removing them from it (aka MT safe peek). 2) Relaxed Tail Sync (RTS) The main difference from original MP/MC algorithm is that tail value is increased not by every thread that finished enqueue/dequeue, but only by the last one. That allows threads to avoid spinning on ring tail value, leaving actual tail value change to the last thread in the update queue. Note that these new sync modes are optional. For current rte_ring users nothing should change (both in terms of API/ABI and performance). Existing sync modes MP/MC,SP/SC kept untouched, set up in the same way (via flags and _init_), and MP/MC remains as default one. The only thing that changed: Format of prod/cons now could differ depending on mode selected at _init_. So user has to stick with one sync model through whole ring lifetime. In other words, user can't create a ring for let say SP mode and then in the middle of data-path change his mind and start using MP_RTS mode. For existing modes (SP/MP, SC/MC) format remains the same and user can still use them interchangeably, though of course it is an error prone practice. Test results on IA (see below) show significant improvements for average enqueue/dequeue op times on overcommitted systems. For 'classic' DPDK deployments (one thread per core) original MP/MC algorithm still shows best numbers, though for 64-bit target RTS numbers are not that far away. Numbers were produced by new UT test-case: ring_stress_autotest, i.e.: echo ring_stress_autotest | ./dpdk-test -n 4 --lcores='...' X86_64 @ Intel(R) Xeon(R) Platinum 8160 CPU @ 2.10GHz DEQ+ENQ average cycles/obj MP/MC HTS RTS 1thread@1core(--lcores=6-7) 8.00 8.15 8.99 2thread@2core(--lcores=6-8) 19.14 19.61 20.35 4thread@4core(--lcores=6-10) 29.43 29.79 31.82 8thread@8core(--lcores=6-14) 110.59 192.81 119.50 16thread@16core(--lcores=6-22) 461.03 813.12 495.59 32thread/@32core(--lcores='6-22,55-70') 982.90 1972.38 1160.51 2thread@1core(--lcores='6,(10-11)@7' 20140.50 23.58 25.14 4thread@2core(--lcores='6,(10-11)@7,(20-21)@8' 153680.60 76.88 80.05 8thread@2core(--lcores='6,(10-13)@7,(20-23)@8' 280314.32 294.72 318.79 16thread@2core(--lcores='6,(10-17)@7,(20-27)@8' 643176.59 1144.02 1175.14 32thread@2core(--lcores='6,(10-25)@7,(30-45)@8' 4264238.80 4627.48 4892.68 8thread@2core(--lcores='6,(10-17)@(7,8))' 321085.98 298.59 307.47 16thread@4core(--lcores='6,(20-35)@(7-10))' 1900705.61 575.35 678.29 32thread@4core(--lcores='6,(20-51)@(7-10))' 5510445.85 2164.36 2714.12 i686 @ Intel(R) Xeon(R) Platinum 8160 CPU @ 2.10GHz DEQ+ENQ average cycles/obj MP/MC HTS RTS 1thread@1core(--lcores=6-7) 7.85 12.13 11.31 2thread@2core(--lcores=6-8) 17.89 24.52 21.86 8thread@8core(--lcores=6-14) 32.58 354.20 54.58 32thread/@32core(--lcores='6-22,55-70') 813.77 6072.41 2169.91 2thread@1core(--lcores='6,(10-11)@7' 16095.00 36.06 34.74 8thread@2core(--lcores='6,(10-13)@7,(20-23)@8' 1140354.54 346.61 361.57 16thread@2core(--lcores='6,(10-17)@7,(20-27)@8' 1920417.86 1314.90 1416.65 8thread@2core(--lcores='6,(10-17)@(7,8))' 594358.61 332.70 357.74 32thread@4core(--lcores='6,(20-51)@(7-10))' 5319896.86 2836.44 3028.87 Konstantin Ananyev (9): test/ring: add contention stress test ring: prepare ring to allow new sync schemes ring: introduce RTS ring mode test/ring: add contention stress test for RTS ring ring: introduce HTS ring mode test/ring: add contention stress test for HTS ring ring: introduce peek style API test/ring: add stress test for MT peek API test/ring: add functional tests for new sync modes app/test/Makefile | 5 + app/test/meson.build | 5 + app/test/test_pdump.c | 6 +- app/test/test_ring.c | 93 ++++-- app/test/test_ring_hts_stress.c | 32 ++ app/test/test_ring_mpmc_stress.c | 31 ++ app/test/test_ring_peek_stress.c | 43 +++ app/test/test_ring_rts_stress.c | 32 ++ app/test/test_ring_stress.c | 57 ++++ app/test/test_ring_stress.h | 38 +++ app/test/test_ring_stress_impl.h | 396 ++++++++++++++++++++++ devtools/libabigail.abignore | 7 + lib/librte_pdump/rte_pdump.c | 2 +- lib/librte_port/rte_port_ring.c | 12 +- lib/librte_ring/Makefile | 8 +- lib/librte_ring/meson.build | 11 +- lib/librte_ring/rte_ring.c | 114 ++++++- lib/librte_ring/rte_ring.h | 243 ++++++++------ lib/librte_ring/rte_ring_c11_mem.h | 44 +++ lib/librte_ring/rte_ring_core.h | 181 ++++++++++ lib/librte_ring/rte_ring_elem.h | 141 ++++++-- lib/librte_ring/rte_ring_generic.h | 48 +++ lib/librte_ring/rte_ring_hts.h | 332 ++++++++++++++++++ lib/librte_ring/rte_ring_hts_c11_mem.h | 207 ++++++++++++ lib/librte_ring/rte_ring_peek.h | 446 +++++++++++++++++++++++++ lib/librte_ring/rte_ring_rts.h | 439 ++++++++++++++++++++++++ lib/librte_ring/rte_ring_rts_c11_mem.h | 179 ++++++++++ 27 files changed, 2978 insertions(+), 174 deletions(-) create mode 100644 app/test/test_ring_hts_stress.c create mode 100644 app/test/test_ring_mpmc_stress.c create mode 100644 app/test/test_ring_peek_stress.c create mode 100644 app/test/test_ring_rts_stress.c create mode 100644 app/test/test_ring_stress.c create mode 100644 app/test/test_ring_stress.h create mode 100644 app/test/test_ring_stress_impl.h create mode 100644 lib/librte_ring/rte_ring_core.h create mode 100644 lib/librte_ring/rte_ring_hts.h create mode 100644 lib/librte_ring/rte_ring_hts_c11_mem.h create mode 100644 lib/librte_ring/rte_ring_peek.h create mode 100644 lib/librte_ring/rte_ring_rts.h create mode 100644 lib/librte_ring/rte_ring_rts_c11_mem.h -- 2.17.1