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 908E1A053C for ; Fri, 31 Jul 2020 13:55:31 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 527761C00D; Fri, 31 Jul 2020 13:55:31 +0200 (CEST) Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by dpdk.org (Postfix) with ESMTP id 68FE311A2; Fri, 31 Jul 2020 13:55:27 +0200 (CEST) IronPort-SDR: mthjHDR4IlOx5LB9aULR6Yaxkova9sjk7+BuIfyGTNG6an+nyUsaUMkkjIc9GDCr99Ou3lMunk BYcwpUtjFyNw== X-IronPort-AV: E=McAfee;i="6000,8403,9698"; a="149588635" X-IronPort-AV: E=Sophos;i="5.75,418,1589266800"; d="scan'208";a="149588635" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Jul 2020 04:55:26 -0700 IronPort-SDR: Q9Kwaz2Km9W2P3OhiiUEFfgPGDi+q3Q6HocAFb4AQwPb3PGJjWQbxZXezFy6hshoZHKcqEMqPA Thd6Jkq55/fQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,418,1589266800"; d="scan'208";a="331043831" Received: from aburakov-mobl.ger.corp.intel.com (HELO [10.213.220.248]) ([10.213.220.248]) by orsmga007.jf.intel.com with ESMTP; 31 Jul 2020 04:55:24 -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> <34EFBCA9F01B0748BEB6B629CE643AE60D0F695F@dggemm513-mbx.china.huawei.com> From: "Burakov, Anatoly" Message-ID: <21d092c3-83ce-a3f4-2411-193a5f46a111@intel.com> Date: Fri, 31 Jul 2020 12:55:23 +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: <34EFBCA9F01B0748BEB6B629CE643AE60D0F695F@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-stable] [dpdk-dev] [PATCH v2] eal/linux: do not create user mem map repeatedly when it exists 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: , Errors-To: stable-bounces@dpdk.org Sender: "stable" On 30-Jul-20 2:16 PM, wangyunjian wrote: >> -----Original Message----- >> From: Burakov, Anatoly [mailto:anatoly.burakov@intel.com] >> Sent: Monday, July 27, 2020 5:24 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 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. > > What about this implementation? Again, this works, but i feel like specializing it to just merge the exact same maps is missing an opportunity to provide a more general solution that merges same *and* subset maps. > > diff --git a/lib/librte_eal/linux/eal_vfio.c b/lib/librte_eal/linux/eal_vfio.c > index e07979936..8dcb04cd9 100644 > --- a/lib/librte_eal/linux/eal_vfio.c > +++ b/lib/librte_eal/linux/eal_vfio.c > @@ -179,6 +179,19 @@ merge_map(struct user_mem_map *left, struct user_mem_map *right) > return 1; > } > > +/* try merging two same maps into one, return 1 if succeeded */ > +static int > +merge_same_map(struct user_mem_map *left, struct user_mem_map *right) > +{ > + if (memcmp(left, right, sizeof(struct user_mem_map)) != 0) { > + return 0; > + } > + > + memset(right, 0, sizeof(*right)); > + > + return 1; > +} > + > static struct user_mem_map * > find_user_mem_map(struct user_mem_maps *user_mem_maps, uint64_t addr, > uint64_t iova, uint64_t len) > @@ -232,7 +245,7 @@ compact_user_maps(struct user_mem_maps *user_mem_maps) > if (is_null_map(l) || is_null_map(r)) > continue; > > - if (merge_map(l, r)) > + if (merge_map(l, r) || merge_same_map(l, r)) > n_merged++; > } > > Thanks, > Yunjian > >> >>> >>> @@ -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 -- Thanks, Anatoly