From mboxrd@z Thu Jan 1 00:00:00 1970 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 462A0C4707A for ; Fri, 1 Apr 2022 15:37:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350195AbiDAPd3 (ORCPT ); Fri, 1 Apr 2022 11:33:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54038 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350626AbiDAPAX (ORCPT ); Fri, 1 Apr 2022 11:00:23 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8EB46185453; Fri, 1 Apr 2022 07:48:06 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 3E641B82500; Fri, 1 Apr 2022 14:48:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F15BEC34111; Fri, 1 Apr 2022 14:48:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1648824484; bh=xBWEKNFE5H+l+atNx46GIEd2XdhRTc0zdVyHl0dLdTA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=K1/KRL6xBkZ/Uxh1yV4+NAO+t2rtU2Ec1UAyknvazL2XXneTqemqkMhsFGqO/fNul fO4K5xLqxi2zkxCHGWf0zISAMK+4hAJ8e3jmanvZxIT+44jN65R5nXDHy2aF6EvYT7 zX+piFzNcVL748esIHkhmVLZawq3RkzgVAsRjUbkpCn1hWQjeBVnVypedsYlFVoeyJ 5OtZd5SNPB1xCTH2OQbsieIzsnf/XH8pn1/SrtDZR48WZUlb1elbYAxP5/+I/HlrjQ ngMf4wiOlYQmNNoi6o4P+3xF0wo9UO+Wj9fdEro2ommaWPg5Ig+F8FOI0nG5R9z7we EvHzgX1Ivh4tg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Dust Li , "David S . Miller" , Sasha Levin , kgraul@linux.ibm.com, kuba@kernel.org, pabeni@redhat.com, linux-s390@vger.kernel.org, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 4.14 13/22] net/smc: correct settings of RMB window update limit Date: Fri, 1 Apr 2022 10:47:20 -0400 Message-Id: <20220401144729.1955554-13-sashal@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220401144729.1955554-1-sashal@kernel.org> References: <20220401144729.1955554-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Dust Li [ Upstream commit 6bf536eb5c8ca011d1ff57b5c5f7c57ceac06a37 ] rmbe_update_limit is used to limit announcing receive window updating too frequently. RFC7609 request a minimal increase in the window size of 10% of the receive buffer space. But current implementation used: min_t(int, rmbe_size / 10, SOCK_MIN_SNDBUF / 2) and SOCK_MIN_SNDBUF / 2 == 2304 Bytes, which is almost always less then 10% of the receive buffer space. This causes the receiver always sending CDC message to update its consumer cursor when it consumes more then 2K of data. And as a result, we may encounter something like "TCP silly window syndrome" when sending 2.5~8K message. This patch fixes this using max(rmbe_size / 10, SOCK_MIN_SNDBUF / 2). With this patch and SMC autocorking enabled, qperf 2K/4K/8K tcp_bw test shows 45%/75%/40% increase in throughput respectively. Signed-off-by: Dust Li Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/smc/smc_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c index 7dc907a45c68..a28e06c70e52 100644 --- a/net/smc/smc_core.c +++ b/net/smc/smc_core.c @@ -499,7 +499,7 @@ struct smc_buf_desc *smc_buf_get_slot(struct smc_link_group *lgr, */ static inline int smc_rmb_wnd_update_limit(int rmbe_size) { - return min_t(int, rmbe_size / 10, SOCK_MIN_SNDBUF / 2); + return max_t(int, rmbe_size / 10, SOCK_MIN_SNDBUF / 2); } static struct smc_buf_desc *smc_new_buf_create(struct smc_link_group *lgr, -- 2.34.1