From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 3486642361; Wed, 11 Oct 2023 14:44:50 +0200 (CEST) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 22E7B40648; Wed, 11 Oct 2023 14:44:50 +0200 (CEST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by mails.dpdk.org (Postfix) with ESMTP id AF9FD40266 for ; Wed, 11 Oct 2023 14:44:48 +0200 (CEST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id EBCB5C15; Wed, 11 Oct 2023 05:45:28 -0700 (PDT) Received: from ampere-altra-2-2.usa.Arm.com (unknown [10.118.91.160]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 2FE6D3F5A1; Wed, 11 Oct 2023 05:44:48 -0700 (PDT) From: Paul Szczepanek To: dev@dpdk.org Cc: Paul Szczepanek Subject: [RFC v2 0/2] add pointer compression API Date: Wed, 11 Oct 2023 12:43:26 +0000 Message-Id: <20231011124328.4002766-1-paul.szczepanek@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230927150854.3670391-2-paul.szczepanek@arm.com> References: <20230927150854.3670391-2-paul.szczepanek@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org This patchset is proposing adding a new EAL header with utility functions that allow compression of arrays of pointers. When passing caches full of pointers between threads, memory containing the pointers is copied multiple times which is especially costly between cores. A compression method will allow us to shrink the memory size copied. The compression takes advantage of the fact that pointers are usually located in a limited memory region (like a mempool). We can compress them by converting them to offsets from a base memory address. Offsets can be stored in fewer bytes (dictated by the memory region size and alignment of the pointer). For example: an 8 byte aligned pointer which is part of a 32GB memory pool can be stored in 4 bytes. The API is very generic and does not assume mempool pointers, any pointer can be passed in. Compression is based on few and fast operations and especially with vector instructions leveraged creates minimal overhead. The API accepts and returns arrays because the overhead means it only is worth it when done in bulk. Test is added that shows potential performance gain from compression. In this test an array of pointers is passed through a ring between two cores. It shows the gain which is dependent on the bulk operation size. In this synthetic test run on ampere altra a substantial (up to 25%) performance gain is seen if done in bulk size larger than 32. At 32 it breaks even and lower sizes create a small (less than 5%) slowdown due to overhead. In a more realistic mock application running the l3 forwarding dpdk example that works in pipeline mode this translated into a ~5% throughput increase on an ampere altra. v2: * addressed review comments (style, explanations and typos) * lowered bulk iterations closer to original numbers to keep runtime short * fixed pointer size warning on 32-bit arch Paul Szczepanek (2): eal: add pointer compression functions test: add pointer compress tests to ring perf test .mailmap | 1 + app/test/test_ring.h | 59 +++++- app/test/test_ring_perf.c | 324 ++++++++++++++++++----------- lib/eal/include/meson.build | 1 + lib/eal/include/rte_ptr_compress.h | 160 ++++++++++++++ 5 files changed, 421 insertions(+), 124 deletions(-) create mode 100644 lib/eal/include/rte_ptr_compress.h -- 2.25.1