From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) by dpdk.org (Postfix) with ESMTP id ECFC32BA5 for ; Wed, 28 Mar 2018 10:55:11 +0200 (CEST) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 28 Mar 2018 01:55:09 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.48,370,1517904000"; d="scan'208";a="27650356" Received: from tanjianf-mobl.ccr.corp.intel.com (HELO [10.67.64.59]) ([10.67.64.59]) by fmsmga007.fm.intel.com with ESMTP; 28 Mar 2018 01:55:08 -0700 To: "Van Haaren, Harry" , Thomas Monjalon References: <3396888.LEadjR7LpM@xps> <2563064.olffpIeeN1@xps> Cc: "Burakov, Anatoly" , "dev@dpdk.org" , "Ananyev, Konstantin" From: "Tan, Jianfeng" Message-ID: <944ebaf4-6dc3-5069-1d7e-2ee7bbcd8adc@intel.com> Date: Wed, 28 Mar 2018 16:55:07 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] [PATCH v6 2/2] eal: add asynchronous request API to DPDK IPC 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, 28 Mar 2018 08:55:12 -0000 Hi Thomas and Harry, On 3/28/2018 4:22 PM, Van Haaren, Harry wrote: >> From: Thomas Monjalon [mailto:thomas@monjalon.net] >> Sent: Wednesday, March 28, 2018 8:30 AM >> To: Tan, Jianfeng >> Cc: Burakov, Anatoly ; dev@dpdk.org; Ananyev, >> Konstantin ; Van Haaren, Harry >> >> Subject: Re: [dpdk-dev] [PATCH v6 2/2] eal: add asynchronous request API to >> DPDK IPC >> >> 28/03/2018 04:08, Tan, Jianfeng: >>> Hi Thomas , >>> >>> From: Thomas Monjalon [mailto:thomas@monjalon.net] >>>> 27/03/2018 15:59, Anatoly Burakov: >>>>> Under the hood, we create a separate thread to deal with replies to >>>>> asynchronous requests, that will just wait to be notified by the >>>>> main thread, or woken up on a timer. >>>> I really don't like that a library is creating a thread. >>>> We don't even know where the thread is created (which core). >>>> Can it be a rte_service? or in the interrupt thread? >>> Agree that we'd better not adding so many threads in a library. >>> >>> I was considering to merge all the threads into the interrupt thread, >> however, we don't have an interrupt thread in freebsd. Further, we don't >> implement alarm API in freebsd. That's why I tend to current implementation, >> and optimize it later. >> >> I would prefer we improve the current code now instead of polluting more >> with more uncontrolled threads. >> >>> For rte_service, it may be not a good idea to reply on it as it needs >> explicit API calls to setup. >> >> I don't see the issue of the explicit API. >> The IPC is a new service. My concern is that not every DPDK application sets up rte_service, but IPC will be used for very fundamental functions, like memory allocation. We could not possibly ask all DPDK applications to add rte_service now. And also take Harry's comments below into consideration, most likely, we will move these threads into interrupt thread now by adding > Although I do like to see new services, if we want to enable "core" dpdk functionality with Services, we need a proper designed solution for that. Service cores is not intended for "occasional" work - there is no method to block and sleep on a specific service until work becomes available, so this would imply a busy-polling. Using a service (hence busy polling) for rte_malloc()-based memory mapping requests is inefficient, and total overkill :) > > For this patch I suggest to use some blocking-read capable mechanism. The problem here is that we add too many threads; blocking-read does not decrease # of threads. > > The above said, in the longer term it would be good to have a design that allows new file-descriptors to be added to a "dpdk core" thread, which performs occasional lengthy work if the FD has data available. Interrupt thread vs rte_service, which is the direction to go? We actually have some others threads, in vhost and even virtio-user; we can also avoid those threads if we have a clear direction. Thanks, Jianfeng