From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg1-f193.google.com (mail-pg1-f193.google.com [209.85.215.193]) by dpdk.org (Postfix) with ESMTP id 960AD239 for ; Wed, 16 Jan 2019 01:26:30 +0100 (CET) Received: by mail-pg1-f193.google.com with SMTP id s198so1976367pgs.2 for ; Tue, 15 Jan 2019 16:26:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=ANtX7Wg13pa0xXfgXkps0pfJdkzc03P4oG6PAEAb9wk=; b=k/uMg0uSSFc/GrxUzCqRpHuYdsRCw48j8BtPH/8WIWU6ByXe34yMeaEzLRdbekQy6t OQkF+h/5ZXn+WjA0x0roYpog6og28D/pNJsmgICRdCtc71PgnsLmFLJPvqzuaVCZ3DT0 CIrLsQAv3liuNr45CKqSMBuosZZ7+fTVpQ+h9icT4AsKwwsXbaNACxUxDT6LZ4DA9icu npifkh4RXpgdPwaLbLT8Wcmp1jPEGfIR3bNJVrMW/BvZk6OMhEJ046XmW+xc64ldLEes CK28y2KYB/ZDmuyPxAP25r6ui/CyC5SBw1Wk7Wrsr0GX4vyXTcAYtw1sNSPOs6IBYc4A Lskw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=ANtX7Wg13pa0xXfgXkps0pfJdkzc03P4oG6PAEAb9wk=; b=gJOJPJGGbIWWokRvhejURJVw/fypyLpsm+O+OwjocSv2yrCsfJKOtwd7NbG1js1f+S Uylyw7vh5d8aJTpL6sHOgo6yEWqMtk5kfCNBkTrX2ne51llEqT4pXYZBzl4jV9dfqPmj E3CXLwJb2l/S4xOp6knsoshbYeahE6mMKTnmx1ItVWbmDYm1rGifYEm/NxlhveMAFodx AngS6hgoWUeJIHko7+gUtebXT5zaIH9trb2F/XkYeqWpY2ukDnosdMii1qCMujvfVA1F Z4Vi3J+e6q+FHOd06yaOzTtgvtvz13mi5RDsAP1bQjM5EbZLFFxR3mWivKiF5KYyKylo Ejaw== X-Gm-Message-State: AJcUukdsq6HYB5vYfmr2fGXVKlM49Kfmaulg9iPYn1goNLOute6ktsu1 EI4v1TMQRIz1/1dGAoR+WWCAVA== X-Google-Smtp-Source: ALg8bN6I/9mI5M0+Fxa9//G85HJIzGCOupWxBiU5oJmGS2q/2crGifdHE/MShI1oHhJCJmf7sl9/zw== X-Received: by 2002:a63:4e15:: with SMTP id c21mr6267017pgb.50.1547598389375; Tue, 15 Jan 2019 16:26:29 -0800 (PST) Received: from shemminger-XPS-13-9360 ([167.220.59.105]) by smtp.gmail.com with ESMTPSA id k186sm5014435pge.13.2019.01.15.16.26.29 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 15 Jan 2019 16:26:29 -0800 (PST) Date: Tue, 15 Jan 2019 16:26:27 -0800 From: Stephen Hemminger To: Gage Eads Cc: dev@dpdk.org, olivier.matz@6wind.com, arybchenko@solarflare.com, bruce.richardson@intel.com, konstantin.ananyev@intel.com Message-ID: <20190115162627.4219d405@shemminger-XPS-13-9360> In-Reply-To: <20190115235227.14013-1-gage.eads@intel.com> References: <20190110210122.24889-1-gage.eads@intel.com> <20190115235227.14013-1-gage.eads@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] [PATCH v2 0/5] Add non-blocking 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: , X-List-Received-Date: Wed, 16 Jan 2019 00:26:31 -0000 On Tue, 15 Jan 2019 17:52:22 -0600 Gage Eads wrote: > 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 non-blocking ring, on top of which a mempool can run. > Crucially, the non-blocking algorithm relies on a 128-bit compare-and-swap, so > it is limited to x86_64 machines. > > The ring uses more compare-and-swap atomic operations than the regular rte ring: > With no contention, an enqueue of n pointers uses (1 + 2n) CAS operations and a > dequeue of n pointers uses 2. 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 non-blocking ring's. > - Software caching can mitigate the average case performance for ring-based > algorithms. For example, a non-blocking ring based mempool (a likely use case > for this ring) with per-thread caching. > > The non-blocking ring is enabled via a new flag, RING_F_NB. For ease-of-use, > existing ring enqueue/dequeue functions work with both "regular" and > non-blocking rings. > > This patchset also adds non-blocking versions of ring_autotest and > ring_perf_autotest, and a non-blocking ring based mempool. > > This patchset makes ABI and API changes; a deprecation notice will be > posted in a separate commit. > > This patchset depends on the non-blocking stack patchset[1]. > > [1] http://mails.dpdk.org/archives/dev/2019-January/123470.html > > 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 (5): > ring: change head and tail to pointer-width size > ring: add a non-blocking implementation > test_ring: add non-blocking ring autotest > test_ring_perf: add non-blocking ring perf test > mempool/ring: add non-blocking ring handlers > > doc/guides/prog_guide/env_abstraction_layer.rst | 2 +- > drivers/mempool/ring/rte_mempool_ring.c | 58 ++- > lib/librte_eventdev/rte_event_ring.h | 6 +- > lib/librte_ring/Makefile | 2 +- > lib/librte_ring/meson.build | 2 +- > lib/librte_ring/rte_ring.c | 53 ++- > lib/librte_ring/rte_ring.h | 564 ++++++++++++++++++++++-- > lib/librte_ring/rte_ring_generic.h | 16 +- > lib/librte_ring/rte_ring_version.map | 7 + > test/test/test_ring.c | 57 ++- > test/test/test_ring_perf.c | 19 +- > 11 files changed, 699 insertions(+), 87 deletions(-) > Just bumping the version number is not enough. This looks like an ABI breakage for existing users.