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 19FB6C43217 for ; Fri, 1 Apr 2022 14:50:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245425AbiDAOw3 (ORCPT ); Fri, 1 Apr 2022 10:52:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60748 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350050AbiDAOrH (ORCPT ); Fri, 1 Apr 2022 10:47:07 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CC9B62A03F0; Fri, 1 Apr 2022 07:37:00 -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 85CF6B824D8; Fri, 1 Apr 2022 14:36:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2F1BBC340F2; Fri, 1 Apr 2022 14:36:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1648823786; bh=fG9MQxUZVJfuo423h37Uy9a7r2z2UmE9/ApwUfDq85M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fR24yzge4htB+kf5fKwd5FS/VYM07RxS+JN96C1ApphqoFUt6AsGWUdD5HKotJe2S Od36PFCFVwLN1TKwrwM+LpB4ENjNzcNkH0oS5/FXVH12CFflh8RfNe5XoMQKNwKdmk UiF6/2Z4WWhoGcpReOrFUPGZxzogcmux5A9grRLPdjOzhufgYurXxt9p3YCeRrZ7qh 9GPkVBnR0laGdU9VQRjXJ/RCePBPReV0K6UA3XEVpJggxAyFrNZxWdlj2UgDCpB9Vc 7QbMgoeY7xawRo1jJVXV0pLNdcv6hAQa4dVfZlGQELZBzN3NXC60OPhACrZpc0jhLG TtfzN0nyGcNow== 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 5.16 076/109] net/smc: correct settings of RMB window update limit Date: Fri, 1 Apr 2022 10:32:23 -0400 Message-Id: <20220401143256.1950537-76-sashal@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220401143256.1950537-1-sashal@kernel.org> References: <20220401143256.1950537-1-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 d1cdc891c211..f1dc5b914771 100644 --- a/net/smc/smc_core.c +++ b/net/smc/smc_core.c @@ -1904,7 +1904,7 @@ 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); } /* map an rmb buf to a link */ -- 2.34.1