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 3EE4BA04B7; Tue, 13 Oct 2020 21:06:58 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 9B57F1B850; Tue, 13 Oct 2020 21:06:56 +0200 (CEST) Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by dpdk.org (Postfix) with ESMTP id E21B5F64 for ; Tue, 13 Oct 2020 21:06:53 +0200 (CEST) IronPort-SDR: cChYNPMO4VqTX+6Kgxl2VBXkcYx8W4oByl1swPgCKZYCtM5y6xcSccpkmj5K4h5hN1eCnNJbKP XspRn3UN6yAw== X-IronPort-AV: E=McAfee;i="6000,8403,9773"; a="162505498" X-IronPort-AV: E=Sophos;i="5.77,371,1596524400"; d="scan'208";a="162505498" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Oct 2020 12:06:51 -0700 IronPort-SDR: q3E0DArqv93LOKX1Ra9GjgJf2g0h5cvX+0AJQ77sUFOn6nZSzCnCz5TjeLyW0TdOMy5PbYqlpf DBIRGL+uxRfg== X-IronPort-AV: E=Sophos;i="5.77,371,1596524400"; d="scan'208";a="463606671" Received: from vmedvedk-mobl.ger.corp.intel.com (HELO [10.213.214.142]) ([10.213.214.142]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Oct 2020 12:06:49 -0700 To: Michel Machado , Kevin Traynor , Ruifeng Wang , Bruce Richardson , Cody Doucette , Andre Nathan , Qiaobin Fu Cc: "dev@dpdk.org" , Honnappa Nagarahalli , nd References: <20200907081518.46350-1-ruifeng.wang@arm.com> <20200907081518.46350-3-ruifeng.wang@arm.com> <20200915160224.GA825@bricha3-MOBL.ger.corp.intel.com> <81eb8fde-cd4f-1df9-0ebb-05c902b30fe3@intel.com> <48834549-00e9-b762-4915-9a2dd0e5fe1d@redhat.com> <6497770e-9d1c-97c3-3834-84bd96186836@digirati.com.br> <18c44f31-abc0-c0b5-c2fb-76d6166d5237@digirati.com.br> From: "Medvedkin, Vladimir" Message-ID: <9197371c-5e03-4852-d62a-6456f0b762f0@intel.com> Date: Tue, 13 Oct 2020 20:06:47 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.3.1 MIME-Version: 1.0 In-Reply-To: <18c44f31-abc0-c0b5-c2fb-76d6166d5237@digirati.com.br> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Subject: Re: [dpdk-dev] [PATCH 2/2] lpm: hide internal data 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 13/10/2020 18:46, Michel Machado wrote: > On 10/13/20 11:41 AM, Medvedkin, Vladimir wrote: >> Hi Michel, >> >> Could you please describe a condition when LPM gets inconsistent? As I >> can see if there is no free tbl8 it will return -ENOSPC. > >    Consider this simple example, we need to add the following two > prefixes with different next hops: 10.99.0.0/16, 18.99.99.128/25. If the > LPM table is out of tbl8s, the second prefix is not added and Gatekeeper > will make decisions in violation of the policy. The data structure of > the LPM table is consistent, but its content inconsistent with the policy. Aha, thanks. So do I understand correctly that you need to add a set of routes atomically (either the entire set is installed or nothing)? If so, then I would suggest having 2 lpm and switching them atomically after a successful addition. As for now, even if you have enough tbl8's, routes are installed non atomically, i.e. there will be a time gap between adding two routes, so in this time interval the table will be inconsistent with the policy. Also, if new lpm algorithms are added to the DPDK, they won't have such a thing as tbl8. > >    We minimize the need of replacing a LPM table by allocating LPM > tables with the double of what we need (see example here > https://github.com/AltraMayor/gatekeeper/blob/95d1d6e8201861a0d0c698bfd06ad606674f1e07/lua/examples/policy.lua#L172-L183), > but the code must be ready for unexpected needs that may arise in > production. > Usually, the table is initialized with a large enough number of entries, enough to add a possible number of routes. One tbl8 group takes up 1Kb of memory which is nothing comparing to the size of tbl24 which is 64Mb. P.S. consider using rte_fib library, it has a number of advantages over LPM. You can replace the loop in __lookup_fib_bulk() with a bulk lookup call and this will probably increase the speed. >> >> On 13/10/2020 15:58, Michel Machado wrote: >>> Hi Kevin, >>> >>>     We do need fields max_rules and number_tbl8s of struct rte_lpm, >>> so the removal would force us to have another patch to our local copy >>> of DPDK. We'd rather avoid this new local patch because we wish to >>> eventually be in sync with the stock DPDK. >>> >>>     Those fields are needed in Gatekeeper because we found a >>> condition in an ongoing deployment in which the entries of some LPM >>> tables may suddenly change a lot to reflect policy changes. To avoid >>> getting into a state in which the LPM table is inconsistent because >>> it cannot fit all the new entries, we compute the needed parameters >>> to support the new entries, and compare with the current parameters. >>> If the current table doesn't fit everything, we have to replace it >>> with a new LPM table. >>> >>>     If there were a way to obtain the struct rte_lpm_config of a >>> given LPM table, it would cleanly address our need. We have the same >>> need in IPv6 and have a local patch to work around it (see >>> https://github.com/cjdoucette/dpdk/commit/3eaf124a781349b8ec8cd880db26a78115cb8c8f). >>> Thus, an IPv4 and IPv6 solution would be best. >>> >>>     PS: I've added Qiaobin Fu, another Gatekeeper maintainer, to this >>> disscussion. >>> >>> [ ]'s >>> Michel Machado >>> >>> On 10/13/20 9:53 AM, Kevin Traynor wrote: >>>> Hi Gatekeeper maintainers (I think), >>>> >>>> fyi - there is a proposal to remove some members of a struct in DPDK >>>> LPM >>>> API that Gatekeeper is using [1]. It would be only from DPDK 20.11 but >>>> as it's an LTS I guess it would probably hit Debian in a few months. >>>> >>>> The full thread is here: >>>> http://inbox.dpdk.org/dev/20200907081518.46350-1-ruifeng.wang@arm.com/ >>>> >>>> Maybe you can take a look and tell us if they are needed in Gatekeeper >>>> or you can workaround it? >>>> >>>> thanks, >>>> Kevin. >>>> >>>> [1] >>>> https://github.com/AltraMayor/gatekeeper/blob/master/gt/lua_lpm.c#L235-L248 >>>> >>>> >>>> On 09/10/2020 07:54, Ruifeng Wang wrote: >>>>> >>>>>> -----Original Message----- >>>>>> From: Kevin Traynor >>>>>> Sent: Wednesday, September 30, 2020 4:46 PM >>>>>> To: Ruifeng Wang ; Medvedkin, Vladimir >>>>>> ; Bruce Richardson >>>>>> >>>>>> Cc: dev@dpdk.org; Honnappa Nagarahalli >>>>>> ; nd >>>>>> Subject: Re: [dpdk-dev] [PATCH 2/2] lpm: hide internal data >>>>>> >>>>>> On 16/09/2020 04:17, Ruifeng Wang wrote: >>>>>>> >>>>>>>> -----Original Message----- >>>>>>>> From: Medvedkin, Vladimir >>>>>>>> Sent: Wednesday, September 16, 2020 12:28 AM >>>>>>>> To: Bruce Richardson ; Ruifeng Wang >>>>>>>> >>>>>>>> Cc: dev@dpdk.org; Honnappa Nagarahalli >>>>>>>> ; nd >>>>>>>> Subject: Re: [PATCH 2/2] lpm: hide internal data >>>>>>>> >>>>>>>> Hi Ruifeng, >>>>>>>> >>>>>>>> On 15/09/2020 17:02, Bruce Richardson wrote: >>>>>>>>> On Mon, Sep 07, 2020 at 04:15:17PM +0800, Ruifeng Wang wrote: >>>>>>>>>> Fields except tbl24 and tbl8 in rte_lpm structure have no need to >>>>>>>>>> be exposed to the user. >>>>>>>>>> Hide the unneeded exposure of structure fields for better ABI >>>>>>>>>> maintainability. >>>>>>>>>> >>>>>>>>>> Suggested-by: David Marchand >>>>>>>>>> Signed-off-by: Ruifeng Wang >>>>>>>>>> Reviewed-by: Phil Yang >>>>>>>>>> --- >>>>>>>>>>    lib/librte_lpm/rte_lpm.c | 152 >>>>>>>>>> +++++++++++++++++++++++--------------- >>>>>>>> - >>>>>>>>>>    lib/librte_lpm/rte_lpm.h |   7 -- >>>>>>>>>>    2 files changed, 91 insertions(+), 68 deletions(-) >>>>>>>>>> >>>>>>>>> >>>>>>>>>> diff --git a/lib/librte_lpm/rte_lpm.h b/lib/librte_lpm/rte_lpm.h >>>>>>>>>> index 03da2d37e..112d96f37 100644 >>>>>>>>>> --- a/lib/librte_lpm/rte_lpm.h >>>>>>>>>> +++ b/lib/librte_lpm/rte_lpm.h >>>>>>>>>> @@ -132,17 +132,10 @@ struct rte_lpm_rule_info { >>>>>>>>>> >>>>>>>>>>    /** @internal LPM structure. */ >>>>>>>>>>    struct rte_lpm { >>>>>>>>>> -    /* LPM metadata. */ >>>>>>>>>> -    char name[RTE_LPM_NAMESIZE];        /**< Name of the lpm. */ >>>>>>>>>> -    uint32_t max_rules; /**< Max. balanced rules per lpm. */ >>>>>>>>>> -    uint32_t number_tbl8s; /**< Number of tbl8s. */ >>>>>>>>>> -    struct rte_lpm_rule_info rule_info[RTE_LPM_MAX_DEPTH]; /**< >>>>>>>> Rule info table. */ >>>>>>>>>> - >>>>>>>>>>        /* LPM Tables. */ >>>>>>>>>>        struct rte_lpm_tbl_entry tbl24[RTE_LPM_TBL24_NUM_ENTRIES] >>>>>>>>>>                __rte_cache_aligned; /**< LPM tbl24 table. */ >>>>>>>>>>        struct rte_lpm_tbl_entry *tbl8; /**< LPM tbl8 table. */ >>>>>>>>>> -    struct rte_lpm_rule *rules_tbl; /**< LPM rules. */ >>>>>>>>>>    }; >>>>>>>>>> >>>>>>>>> >>>>>>>>> Since this changes the ABI, does it not need advance notice? >>>>>>>>> >>>>>>>>> [Basically the return value point from rte_lpm_create() will be >>>>>>>>> different, and that return value could be used by rte_lpm_lookup() >>>>>>>>> which as a static inline function will be in the binary and using >>>>>>>>> the old structure offsets.] >>>>>>>>> >>>>>>>> >>>>>>>> Agree with Bruce, this patch breaks ABI, so it can't be accepted >>>>>>>> without prior notice. >>>>>>>> >>>>>>> So if the change wants to happen in 20.11, a deprecation notice >>>>>>> should >>>>>>> have been added in 20.08. >>>>>>> I should have added a deprecation notice. This change will have >>>>>>> to wait for >>>>>> next ABI update window. >>>>>>> >>>>>> >>>>>> Do you plan to extend? or is this just speculative? >>>>> It is speculative. >>>>> >>>>>> >>>>>> A quick scan and there seems to be several projects using some of >>>>>> these >>>>>> members that you are proposing to hide. e.g. BESS, NFF-Go, DPVS, >>>>>> gatekeeper. I didn't look at the details to see if they are really >>>>>> needed. >>>>>> >>>>>> Not sure how much notice they'd need or if they update DPDK much, >>>>>> but I >>>>>> think it's worth having a closer look as to how they use lpm and >>>>>> what the >>>>>> impact to them is. >>>>> Checked the projects listed above. BESS, NFF-Go and DPVS don't >>>>> access the members to be hided. >>>>> They will not be impacted by this patch. >>>>> But Gatekeeper accesses the rte_lpm internal members that to be >>>>> hided. Its compilation will be broken with this patch. >>>>> >>>>>> >>>>>>> Thanks. >>>>>>> Ruifeng >>>>>>>>>>    /** LPM RCU QSBR configuration structure. */ >>>>>>>>>> -- >>>>>>>>>> 2.17.1 >>>>>>>>>> >>>>>>>> >>>>>>>> -- >>>>>>>> Regards, >>>>>>>> Vladimir >>>>> >>>> >> -- Regards, Vladimir