From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id AF8F141FCE; Thu, 31 Aug 2023 03:23:49 +0200 (CEST) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 5581D40285; Thu, 31 Aug 2023 03:23:49 +0200 (CEST) Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by mails.dpdk.org (Postfix) with ESMTP id F248840144 for ; Thu, 31 Aug 2023 03:23:47 +0200 (CEST) Received: from kwepemm600004.china.huawei.com (unknown [172.30.72.57]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4Rbk0Y4sQ5z1L9Yd; Thu, 31 Aug 2023 09:22:05 +0800 (CST) Received: from [10.67.121.59] (10.67.121.59) by kwepemm600004.china.huawei.com (7.193.23.242) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Thu, 31 Aug 2023 09:23:44 +0800 Message-ID: Date: Thu, 31 Aug 2023 09:23:44 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH v2 1/2] ethdev: add new symmetric hash function To: "Xueming(Steven) Li" , Ori Kam CC: "dev@dpdk.org" , "fengchengwen@huawei.com" , Ivan Malov References: <20230807115456.17478-1-xuemingl@nvidia.com> <20230827081745.31906-1-xuemingl@nvidia.com> <0926596b-7474-8821-55af-45699d5fc878@huawei.com> From: "lihuisong (C)" In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.67.121.59] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemm600004.china.huawei.com (7.193.23.242) X-CFilter-Loop: Reflected X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org 在 2023/8/30 21:09, Xueming(Steven) Li 写道: > >> -----Original Message----- >> From: lihuisong (C) >> Sent: 8/30/2023 20:42 >> To: Xueming(Steven) Li ; Ori Kam >> Cc: dev@dpdk.org; fengchengwen@huawei.com; Ivan Malov >> >> Subject: Re: [PATCH v2 1/2] ethdev: add new symmetric hash function >> >> >> 在 2023/8/30 16:38, Xueming(Steven) Li 写道: >>>> -----Original Message----- >>>> From: lihuisong (C) >>>> Sent: 8/30/2023 15:51 >>>> To: Xueming(Steven) Li ; Ori Kam >>>> >>>> Cc: dev@dpdk.org; fengchengwen@huawei.com; Ivan Malov >>>> >>>> Subject: Re: [PATCH v2 1/2] ethdev: add new symmetric hash function >>>> >>>> Hi Xueming, >>>> >>>> 在 2023/8/27 16:17, Xueming Li 写道: >>>>> The new symmetric hash function swap src/dst L3 address and >>>>> L4 ports automatically by sorting. >>>>> >>>>> Signed-off-by: Xueming Li >>>>> --- >>>>> lib/ethdev/rte_flow.h | 7 +++++++ >>>>> 1 file changed, 7 insertions(+) >>>>> >>>>> diff --git a/lib/ethdev/rte_flow.h b/lib/ethdev/rte_flow.h index >>>>> 2ebb76dbc0..4f4421ca50 100644 >>>>> --- a/lib/ethdev/rte_flow.h >>>>> +++ b/lib/ethdev/rte_flow.h >>>>> @@ -3196,6 +3196,13 @@ enum rte_eth_hash_function { >>>>> * src or dst address will xor with zero pair. >>>>> */ >>>>> RTE_ETH_HASH_FUNCTION_SYMMETRIC_TOEPLITZ, >>>>> + /** >>>>> + * Symmetric Toeplitz: L3 and L4 fields are sorted prior to >>>>> + * the hash function. >>>>> + * If src_ip > dst_ip, swap src_ip and dst_ip. >>>>> + * If src_port > dst_port, swap src_port and dst_port. >>>>> + */ >>>> If hash result are computed by the order: >> "src_ip+dst_ip+src_port+dst_port" >>>> How to obtain the value of every L3 and L4 field obove? >>>> I still cannot understand how to swap and set these values for these fields? >>> Hash result is computed by order ""src_ip+dst_ip+src_port+dst_port" >>> Here is a detailed explanation of standard hash and symmetric hash by key: >>> https://www.ndsl.kaist.edu/~kyoungsoo/papers/TR-symRSS.pdf >>> >>> If src_ip > dst_ip, swap them, then the input becomes: >>> "dst_ip+src_ip+src_port+dst_port" // please note src and dst IP are >> swapped. >>> Same for L4 ports. >> get it. >> What are the advantages of the symmetric toeplitz sort? >> Or why swap here? > It's a different symmetric hash calculation, hardware can support either/all of them. > > From calculation perspective, the hash result distribution is better, the result is more > suitable to be used as hash table key. I get it now. but I have a question. why not is that if src_ip < dst_ip, then swap src_ip and dst_ip? I guess this is going to have the same effect as you said, right? The symmetric toeplitz sort is not a standard algorithm, is just to enhance the hash result distribution. If what I understand is right, it is better that the new RSS algorithm should works on the one of them ("src_ip > dst_ip" or "src_ip < dst_ip"). > >>>>> + RTE_ETH_HASH_FUNCTION_SYMMETRIC_TOEPLITZ_SORT, >>>>> RTE_ETH_HASH_FUNCTION_MAX, >>>>> }; >>>>>