From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dispatch1-us1.ppe-hosted.com (dispatch1-us1.ppe-hosted.com [148.163.129.52]) by dpdk.org (Postfix) with ESMTP id A902B2C72; Thu, 1 Feb 2018 11:00:23 +0100 (CET) X-Virus-Scanned: Proofpoint Essentials engine Received: from webmail.solarflare.com (uk.solarflare.com [193.34.186.16]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1-us4.ppe-hosted.com (Proofpoint Essentials ESMTP Server) with ESMTPS id 562074C005C; Thu, 1 Feb 2018 10:00:22 +0000 (UTC) Received: from [192.168.38.17] (84.52.114.114) by ukex01.SolarFlarecom.com (10.17.10.4) with Microsoft SMTP Server (TLS) id 15.0.1044.25; Thu, 1 Feb 2018 10:00:16 +0000 To: santosh , Olivier Matz CC: , , References: <1511539591-20966-1-git-send-email-arybchenko@solarflare.com> <1516713372-10572-1-git-send-email-arybchenko@solarflare.com> <1516713372-10572-2-git-send-email-arybchenko@solarflare.com> <20180131164504.cnfgfwo2x3ftxnaj@platinum> <90005aad-1508-44bc-92a4-7c5d5f7b0246@caviumnetworks.com> <53796b3f-b2c2-dcfc-a10b-71ce1a68d3d2@caviumnetworks.com> From: Andrew Rybchenko Message-ID: <618e4eb2-e66c-592c-2065-f86328916d5d@solarflare.com> Date: Thu, 1 Feb 2018 13:00:12 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 MIME-Version: 1.0 In-Reply-To: <53796b3f-b2c2-dcfc-a10b-71ce1a68d3d2@caviumnetworks.com> Content-Language: en-GB X-Originating-IP: [84.52.114.114] X-ClientProxiedBy: ocex03.SolarFlarecom.com (10.20.40.36) To ukex01.SolarFlarecom.com (10.17.10.4) X-TM-AS-Product-Ver: SMEX-11.0.0.1191-8.100.1062-23634.003 X-TM-AS-Result: No--12.509500-0.000000-31 X-TM-AS-User-Approved-Sender: Yes X-TM-AS-User-Blocked-Sender: No X-MDID: 1517479223-HoJqmJ1C1nDK Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit X-Content-Filtered-By: Mailman/MimeDel 2.1.15 Subject: Re: [dpdk-stable] [dpdk-dev] [RFC v2 01/17] mempool: fix phys contig check if populate default skipped X-BeenThere: stable@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches for DPDK stable branches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 01 Feb 2018 10:00:24 -0000 On 02/01/2018 12:30 PM, santosh wrote: > On Thursday 01 February 2018 02:48 PM, Andrew Rybchenko wrote: >> On 02/01/2018 12:09 PM, santosh wrote: >>> On Thursday 01 February 2018 12:24 PM, Andrew Rybchenko wrote: >>>> On 02/01/2018 08:05 AM, santosh wrote: >>>>> On Wednesday 31 January 2018 10:15 PM, Olivier Matz wrote: >>>>>> On Tue, Jan 23, 2018 at 01:15:56PM +0000, Andrew Rybchenko wrote: >>>>>>> There is not specified dependency between rte_mempool_populate_default() >>>>>>> and rte_mempool_populate_iova(). So, the second should not rely on the >>>>>>> fact that the first adds capability flags to the mempool flags. >>>>>>> >>>>>>> Fixes: 65cf769f5e6a ("mempool: detect physical contiguous objects") >>>>>>> Cc: stable@dpdk.org >>>>>>> >>>>>>> Signed-off-by: Andrew Rybchenko >>>>>> Looks good to me. I agree it's strange that the mp->flags are >>>>>> updated with capabilities only in rte_mempool_populate_default(). >>>>>> I see that this behavior is removed later in the patchset since the >>>>>> get_capa() is removed! >>>>>> >>>>>> However maybe this single patch could go in 18.02. >>>>>> +Santosh +Jerin since it's mostly about Octeon. >>>>> rte_mempool_xmem_size should return correct size if MEMPOOL_F_CAPA_BLK_ALIGNED_OBJECTS flag >>>>> is set in 'mp->flags'. Thats why _ops_get_capabilities() called in _populate_default() but not >>>>> at _populate_iova(). >>>>> I think, this 'alone' patch may break octeontx mempool. >>>> The patch does not touch rte_mempool_populate_default(). >>>> _ops_get_capabilities() is still called there before >>>> rte_mempool_xmem_size(). The theoretical problem which >>>> the patch tries to fix is the case when >>>> rte_mempool_populate_default() is not called at all. I.e. application >>>> calls _ops_get_capabilities() to get flags, then, together with >>>> mp->flags, calls rte_mempool_xmem_size() directly, allocates >>>> calculated amount of memory and calls _populate_iova(). >>>> >>> In that case, Application does like below: >>> >>>     /* Get mempool capabilities */ >>>     mp_flags = 0; >>>     ret = rte_mempool_ops_get_capabilities(mp, &mp_flags); >>>     if ((ret < 0) && (ret != -ENOTSUP)) >>>         return ret; >>> >>>     /* update mempool capabilities */ >>>     mp->flags |= mp_flags; >> Above line is not mandatory. "mp->flags | mp_flags" could be simply >> passed to  rte_mempool_xmem_size() below. >> > That depends and again upto application requirement, if app further down > wants to refer mp->flags for _align/_contig then better update to mp->flags. > > But that wasn't the point of discussion, I'm trying to understand that > w/o this patch, whats could be the application level problem? The problem that it is fragile. If application does not use rte_mempool_populate_default() it has to care about addition of mempool capability flags into mempool flags. If it is not done, rte_mempool_populate_iova/virt/iova_tab() functions will work incorrectly since F_CAPA_PHYS_CONTIG and F_CAPA_BLK_ALIGNED_OBJECTS are missing. The idea of the patch is to make it a bit more robust. I have no idea how it can break something. If capability flags are already there - no problem. If no, just make sure that we locally have them.