From patchwork Fri Nov 25 01:00:26 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chao Leng X-Patchwork-Id: 13055446 X-Patchwork-Delegate: jgg@ziepe.ca Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E1498C4332F for ; Fri, 25 Nov 2022 01:00:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229589AbiKYBAb (ORCPT ); Thu, 24 Nov 2022 20:00:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33662 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229590AbiKYBAb (ORCPT ); Thu, 24 Nov 2022 20:00:31 -0500 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BEB1CB7F1 for ; Thu, 24 Nov 2022 17:00:29 -0800 (PST) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.57]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4NJGjk4b6gz15Md7; Fri, 25 Nov 2022 08:59:54 +0800 (CST) Received: from huawei.com (10.29.88.127) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 25 Nov 2022 09:00:27 +0800 From: Chao Leng To: , CC: , Subject: [PATCH] infiniband:cma: change iboe packet life time from 18 to 16 Date: Fri, 25 Nov 2022 09:00:26 +0800 Message-ID: <20221125010026.755-1-lengchao@huawei.com> X-Mailer: git-send-email 2.16.4 MIME-Version: 1.0 X-Originating-IP: [10.29.88.127] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org The ack timeout retransmission time is affected by the following two factors: one is packet life time, another is the HCA processing time. Now the default packet lifetime(CMA_IBOE_PACKET_LIFETIME) is 18. That means the minimum ack timeout is 2 seconds(2^(18+1)*4us=2.097seconds). The packet lifetime means the maximum transmission time of packets on the network, 2 seconds is too long. Assume the network is a clos topology with three layers, every packet will pass through five hops of switches. Assume the buffer of every switch is 128MB and the port transmission rate is 25 Gbit/s, the maximum transmission time of the packet is 200ms(128MB*5/25Gbit/s). Add double redundancy, it is less than 500ms. So change the CMA_IBOE_PACKET_LIFETIME to 16, the maximum transmission time of the packet will be about 500+ms, it is long enough. Signed-off-by: Chao Leng --- drivers/infiniband/core/cma.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c index cc2222b85c88..2f5b5e6f3d11 100644 --- a/drivers/infiniband/core/cma.c +++ b/drivers/infiniband/core/cma.c @@ -47,7 +47,7 @@ MODULE_LICENSE("Dual BSD/GPL"); #define CMA_CM_RESPONSE_TIMEOUT 20 #define CMA_MAX_CM_RETRIES 15 #define CMA_CM_MRA_SETTING (IB_CM_MRA_FLAG_DELAY | 24) -#define CMA_IBOE_PACKET_LIFETIME 18 +#define CMA_IBOE_PACKET_LIFETIME 16 #define CMA_PREFERRED_ROCE_GID_TYPE IB_GID_TYPE_ROCE_UDP_ENCAP static const char * const cma_events[] = {