From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id 43927A0524; Mon, 27 Jul 2020 11:24:39 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id B477A1BFF5; Mon, 27 Jul 2020 11:24:38 +0200 (CEST) Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by dpdk.org (Postfix) with ESMTP id E1EE11BFE0; Mon, 27 Jul 2020 11:24:35 +0200 (CEST) IronPort-SDR: d/RnKbQdubViGKEGK8h6Q1B/pJ35bWm7Shy0H2NyYnmY0KftNfelNhkj3nbBcgQ9xAGRwsm49h RzVKsrLV5oPg== X-IronPort-AV: E=McAfee;i="6000,8403,9694"; a="130528886" X-IronPort-AV: E=Sophos;i="5.75,402,1589266800"; d="scan'208";a="130528886" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Jul 2020 02:24:34 -0700 IronPort-SDR: olzxm06AD9LDJFFMxnee/meujt/pEgwwSQo/AQQQSUfWD6wWmSPrBjopsdH9B6KY81nZQMT/fP 8MyQy5GFrhyA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,402,1589266800"; d="scan'208";a="329613220" Received: from aburakov-mobl.ger.corp.intel.com (HELO [10.214.224.54]) ([10.214.224.54]) by orsmga007.jf.intel.com with ESMTP; 27 Jul 2020 02:24:31 -0700 To: wangyunjian , "dev@dpdk.org" , "david.marchand@redhat.com" Cc: "Lilijun (Jerry)" , xudingke , "stable@dpdk.org" References: <1595515713-24640-1-git-send-email-wangyunjian@huawei.com> <34EFBCA9F01B0748BEB6B629CE643AE60D0EAAD8@dggemm513-mbx.china.huawei.com> From: "Burakov, Anatoly" Message-ID: Date: Mon, 27 Jul 2020 10:24:29 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <34EFBCA9F01B0748BEB6B629CE643AE60D0EAAD8@dggemm513-mbx.china.huawei.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] [PATCH v2] eal/linux: do not create user mem map repeatedly when it exists 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: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 25-Jul-20 10:59 AM, wangyunjian wrote: >> -----Original Message----- >> From: Burakov, Anatoly [mailto:anatoly.burakov@intel.com] >> Sent: Friday, July 24, 2020 9:25 PM >> To: wangyunjian ; dev@dpdk.org; >> david.marchand@redhat.com >> Cc: Lilijun (Jerry) ; xudingke >> ; stable@dpdk.org >> Subject: Re: [dpdk-dev] [PATCH v2] eal/linux: do not create user mem map >> repeatedly when it exists >> >> On 23-Jul-20 3:48 PM, wangyunjian wrote: >>> From: Yunjian Wang >>> >>> Currently, we will create new user mem map entry for the same memory >>> segment, but in fact it has already been added to the user mem maps. >>> It's not necessary to create it twice. >>> >>> To resolve the issue, add support to remove the same entry in the >>> function compact_user_maps(). >>> >>> Fixes: 0cbce3a167f1 ("vfio: skip DMA map failure if already mapped") >>> Cc: stable@dpdk.org >>> >>> Signed-off-by: Yunjian Wang >>> --- >>> v2: >>> * Remove the same entry in the function compact_user_maps() >>> --- >>> lib/librte_eal/linux/eal_vfio.c | 5 +++++ >>> 1 file changed, 5 insertions(+) >>> >>> diff --git a/lib/librte_eal/linux/eal_vfio.c b/lib/librte_eal/linux/eal_vfio.c >>> index abb12a354..df99307b7 100644 >>> --- a/lib/librte_eal/linux/eal_vfio.c >>> +++ b/lib/librte_eal/linux/eal_vfio.c >>> @@ -167,6 +167,10 @@ adjust_map(struct user_mem_map *src, struct >> user_mem_map *end, >>> static int >>> merge_map(struct user_mem_map *left, struct user_mem_map *right) >>> { >>> + /* merge the same maps into one */ >>> + if (memcmp(left, right, sizeof(struct user_mem_map)) == 0) >>> + goto out; >>> + >> >> merge_map looks for adjacent maps only, but does not handle maps that >> are wholly contained within one another ("the same map" also matches >> this definition). wouldn't it be better to check for that instead of >> *just* handling identical maps? > > What about using the initial implementation? > We don't create new user mem map entry for the same memory segment. I don't like this implementation because it relies on particulars of how VFIO mapping work without explicitly specifying them. I.e. it's prone to breaking when changing code. That's not even mentioning that we have no guarantees on kernel behavior in that particular case being identical on all supported platforms. I would honestly prefer an explicit compaction over implicit one. > > @@ -1828,6 +1828,13 @@ container_dma_map(struct vfio_config *vfio_cfg, uint64_t vaddr, uint64_t iova, > ret = -1; > goto out; > } > + > + /* we don't need create new user mem map entry > + * for the same memory segment. > + */ > + if (errno == EBUSY || errno == EEXIST) > + goto out; > + > /* create new user mem map entry */ > new_map = &user_mem_maps->maps[user_mem_maps->n_maps++]; > new_map->addr = vaddr; > > Thanks, > Yunjian >> >>> if (left->addr + left->len != right->addr) >>> return 0; >>> if (left->iova + left->len != right->iova) >>> @@ -174,6 +178,7 @@ merge_map(struct user_mem_map *left, struct >> user_mem_map *right) >>> >>> left->len += right->len; >>> >>> +out: >>> memset(right, 0, sizeof(*right)); >>> >>> return 1; >>> >> >> >> -- >> Thanks, >> Anatoly -- Thanks, Anatoly