From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <dev-bounces@dpdk.org> Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 7E6AFA034F; Thu, 29 Jul 2021 15:33:39 +0200 (CEST) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 0695740DFB; Thu, 29 Jul 2021 15:33:39 +0200 (CEST) Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by mails.dpdk.org (Postfix) with ESMTP id B3EFF40687 for <dev@dpdk.org>; Thu, 29 Jul 2021 15:33:36 +0200 (CEST) Received: from dggemv711-chm.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4GbBGj1srDzchsP; Thu, 29 Jul 2021 21:30:05 +0800 (CST) Received: from dggpeml500024.china.huawei.com (7.185.36.10) by dggemv711-chm.china.huawei.com (10.1.198.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 29 Jul 2021 21:33:34 +0800 Received: from [10.40.190.165] (10.40.190.165) by dggpeml500024.china.huawei.com (7.185.36.10) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 29 Jul 2021 21:33:34 +0800 To: Bruce Richardson <bruce.richardson@intel.com> CC: <thomas@monjalon.net>, <ferruh.yigit@intel.com>, <jerinj@marvell.com>, <jerinjacobk@gmail.com>, <andrew.rybchenko@oktetlabs.ru>, <dev@dpdk.org>, <mb@smartsharesystems.com>, <nipun.gupta@nxp.com>, <hemant.agrawal@nxp.com>, <maxime.coquelin@redhat.com>, <honnappa.nagarahalli@arm.com>, <david.marchand@redhat.com>, <sburla@marvell.com>, <pkapoor@marvell.com>, <konstantin.ananyev@intel.com> References: <1625231891-2963-1-git-send-email-fengchengwen@huawei.com> <1627357200-15291-1-git-send-email-fengchengwen@huawei.com> <1627357200-15291-2-git-send-email-fengchengwen@huawei.com> <YQE75ZjolP5Rmt/O@bricha3-MOBL.ger.corp.intel.com> <9da78c1f-c2e4-cf71-9d07-dd539a16c1d0@huawei.com> <YQJxmgnxbyetQa6S@bricha3-MOBL.ger.corp.intel.com> From: fengchengwen <fengchengwen@huawei.com> Message-ID: <383930f2-5612-fdc9-b9e3-7cde2755db77@huawei.com> Date: Thu, 29 Jul 2021 21:33:33 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <YQJxmgnxbyetQa6S@bricha3-MOBL.ger.corp.intel.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.40.190.165] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpeml500024.china.huawei.com (7.185.36.10) X-CFilter-Loop: Reflected Subject: Re: [dpdk-dev] [PATCH v11 1/2] dmadev: introduce DMA device library X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions <dev.dpdk.org> List-Unsubscribe: <https://mails.dpdk.org/options/dev>, <mailto:dev-request@dpdk.org?subject=unsubscribe> List-Archive: <http://mails.dpdk.org/archives/dev/> List-Post: <mailto:dev@dpdk.org> List-Help: <mailto:dev-request@dpdk.org?subject=help> List-Subscribe: <https://mails.dpdk.org/listinfo/dev>, <mailto:dev-request@dpdk.org?subject=subscribe> Errors-To: dev-bounces@dpdk.org Sender: "dev" <dev-bounces@dpdk.org> Thanks, comment inline On 2021/7/29 17:15, Bruce Richardson wrote: > On Thu, Jul 29, 2021 at 09:26:31AM +0800, fengchengwen wrote: >> Thanks, inline comment >> >> On 2021/7/28 19:13, Bruce Richardson wrote: >>> On Tue, Jul 27, 2021 at 11:39:59AM +0800, Chengwen Feng wrote: >>>> This patch introduce 'dmadevice' which is a generic type of DMA >>>> device. >>>> >>>> The APIs of dmadev library exposes some generic operations which can >>>> enable configuration and I/O with the DMA devices. >>>> >>>> Signed-off-by: Chengwen Feng <fengchengwen@huawei.com> >>>> Acked-by: Bruce Richardson <bruce.richardson@intel.com> >>>> Acked-by: Morten Brørup <mb@smartsharesystems.com> >>>> --- >>> >>> Thanks for this. Before it gets merged, I believe it needs to be split >>> further into multiple patches (say 4 or so) rather than adding the whole >>> lib in one go. >>> >>> Normally, I believe the split would be something like: >>> * basic device structures and infrastructure e.g. alloc and release >>> functions >>> * device config functions (and structures to go along with them) >>> such as configure and queue_setup >>> * data plane functions >>> >> >> I will try for it >> Maybe one patch for public file, one for pmd header file, one for >> implementation, and last for doc. >> >>> Documentation would be included in each of the patches, rather than done as >>> a block at the end. >>> >>> Besides that, I have one small additional requests for the API. Based off >>> feedback for ioat driver, we added in the following function to that API, >>> and we probably need something similar in dmadev: >>> >>> rte_ioat_burst_capacity() >>> >>> For our implementation this returns the number of elements that can be >>> enqueued to the ring, at least for the current burst/batch of packets. We >>> did the API this way because there can be additional limits beyond ring >>> size on each individual burst beyond just the raw ring capacity, e.g. even >>> if there are 4k ring elements free, there may be limits on the max burst >>> size the hardware can do, or limits on the number of outstanding >>> batches etc. >>> >>> Therefore can I request the addition of rte_dmadev_burst_capacity() [or >>> something similarly named] to the basic dmadev API set. For most hardware, >>> I think this will likely be the remaining free ring size, but I don't >>> believe the API should commit to that. The use case it was added for was to >>> enable an application which needs to do a multi-copy operation to check >>> that all copies can fit or not before enqueuing the first one. This is >>> important for hardware that doesn't have scatter-gather list support. >> >> Remaining capacity can be inferred by ring_idx which return from enqueue and >> dequeue APIs. >> So I don't think this API needs to be added. >> > > Yes, the app can always track it itself, but I still see value in adding > this API. However, so long as you are open to having it added later, it > doesn't matter if it's not present in the first versions of this API merged > in. Got it, I think we could discuss later when we adapt more drivers. > > /Bruce > . >