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 B54CFC433F5 for ; Fri, 1 Apr 2022 15:52:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344206AbiDAPyC (ORCPT ); Fri, 1 Apr 2022 11:54:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33066 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350288AbiDAO7b (ORCPT ); Fri, 1 Apr 2022 10:59:31 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 622C55A5A8; Fri, 1 Apr 2022 07:47:03 -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 dfw.source.kernel.org (Postfix) with ESMTPS id E98D160AC9; Fri, 1 Apr 2022 14:47:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2958FC34111; Fri, 1 Apr 2022 14:47:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1648824422; bh=6S0elGmAHKM1RwkqoLD2Od7pEym8vSOjGtE6SypzUts=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=G+V1AAw1co1PgYeber9trcpIvgPrsi2frsD398Fbk9PGJMwnoxLoWEoIauQOGyHjM j4Ssx0ea1Qt0hdsCzGWAkoCnWOd/1SrDXi6kT/7+chKzOJrBAutU7Ubs/0c6lu8xKm ECsqFbcyUTEksOonwFnBHzDo9YtXEDMZYhYqNyNsEC9QC4OfzirVZViZqIOrPAObTP +D+S9O+4ARbozTT1/J5mOYsl+aJHNH6vPSZmtxuKTumUcn6yrygw/JjxPD2GmRcGye HHvLjTSNw7b4Ws7+/G285Anj0l7FbxfzVyv1h6xVls17xJK+ENZ+YleMz4A6Q47mu4 /O+BBaIcLoWCQ== 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 4.19 19/29] net/smc: correct settings of RMB window update limit Date: Fri, 1 Apr 2022 10:46:02 -0400 Message-Id: <20220401144612.1955177-19-sashal@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220401144612.1955177-1-sashal@kernel.org> References: <20220401144612.1955177-1-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: linux-s390@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 6add3094ea9e..4d421407d6fc 100644 --- a/net/smc/smc_core.c +++ b/net/smc/smc_core.c @@ -709,7 +709,7 @@ static struct smc_buf_desc *smc_buf_get_slot(int compressed_bufsize, */ 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 *smcr_new_buf_create(struct smc_link_group *lgr, -- 2.34.1