From patchwork Wed Sep 27 15:08:52 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Szczepanek X-Patchwork-Id: 194 Return-Path: X-Original-To: patchwork@inbox.dpdk.org Delivered-To: patchwork@inbox.dpdk.org Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 322E142653; Wed, 27 Sep 2023 17:09:49 +0200 (CEST) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 081384029B; Wed, 27 Sep 2023 17:09:49 +0200 (CEST) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by mails.dpdk.org (Postfix) with ESMTP id 8CC3E402D0 for ; Wed, 27 Sep 2023 17:09:47 +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 0FC0B1FB; Wed, 27 Sep 2023 08:10:25 -0700 (PDT) Received: from ampere-altra-2-1.usa.Arm.com (ampere-altra-2-1.usa.arm.com [10.118.91.158]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id DCD363F59C; Wed, 27 Sep 2023 08:09:46 -0700 (PDT) From: Paul Szczepanek To: dev@dpdk.org Cc: Paul Szczepanek Subject: [RFC 0/2] add pointer compression API Date: Wed, 27 Sep 2023 15:08:52 +0000 Message-Id: <20230927150854.3670391-1-paul.szczepanek@arm.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 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. 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 | 158 ++++++++++++++ 5 files changed, 419 insertions(+), 124 deletions(-) create mode 100644 lib/eal/include/rte_ptr_compress.h