From patchwork Wed Apr 1 16:16:27 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 228513 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0FD8BC2D0F3 for ; Wed, 1 Apr 2020 16:23:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B881A20857 for ; Wed, 1 Apr 2020 16:23:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585758191; bh=wXpqnL02q/qtDYC/7Q+JdsgSjofZ4psHDjwuCxNroPE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=X/cccuW8UHl3z+Lu1wE4HANX8TLdzUWMUmBnZqBGryTobyIlyItIEgAeodCjcLXIF YjMvkstTDEkFQLFiblo50+g9ANc2bR8DhUb1vwAP2vU5A6m2Eobnan42c7aCMo4jPG 06un77H4ljcz3Xg593iXYUgLqtsYvOCCnxxpWIsU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387562AbgDAQXF (ORCPT ); Wed, 1 Apr 2020 12:23:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:46310 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733250AbgDAQXF (ORCPT ); Wed, 1 Apr 2020 12:23:05 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 2439621582; Wed, 1 Apr 2020 16:23:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585758184; bh=wXpqnL02q/qtDYC/7Q+JdsgSjofZ4psHDjwuCxNroPE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=T2ITqPlT4ID97AVimigOhRyVyMjFzKBVMqVliflxfSwvTSWu+qZz/DyHnhpfuYog9 2sXyLqpL3TwJV+olvJQRbDbFF7Zql4asqH4jtMZJU2TH+RqZ97F1TAtDUaCIghNYp/ G00RsB6ADLXH+3rgq8au/PjRbyvg/mGI9RRlyHuE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Zh-yuan Ye , Vinicius Costa Gomes , "David S. Miller" Subject: [PATCH 4.19 011/116] net: cbs: Fix software cbs to consider packet sending time Date: Wed, 1 Apr 2020 18:16:27 +0200 Message-Id: <20200401161543.523486071@linuxfoundation.org> X-Mailer: git-send-email 2.26.0 In-Reply-To: <20200401161542.669484650@linuxfoundation.org> References: <20200401161542.669484650@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Zh-yuan Ye [ Upstream commit 961d0e5b32946703125964f9f5b6321d60f4d706 ] Currently the software CBS does not consider the packet sending time when depleting the credits. It caused the throughput to be Idleslope[kbps] * (Port transmit rate[kbps] / |Sendslope[kbps]|) where Idleslope * (Port transmit rate / (Idleslope + |Sendslope|)) = Idleslope is expected. In order to fix the issue above, this patch takes the time when the packet sending completes into account by moving the anchor time variable "last" ahead to the send completion time upon transmission and adding wait when the next dequeue request comes before the send completion time of the previous packet. changelog: V2->V3: - remove unnecessary whitespace cleanup - add the checks if port_rate is 0 before division V1->V2: - combine variable "send_completed" into "last" - add the comment for estimate of the packet sending Fixes: 585d763af09c ("net/sched: Introduce Credit Based Shaper (CBS) qdisc") Signed-off-by: Zh-yuan Ye Reviewed-by: Vinicius Costa Gomes Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/sched/sch_cbs.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) --- a/net/sched/sch_cbs.c +++ b/net/sched/sch_cbs.c @@ -185,6 +185,11 @@ static struct sk_buff *cbs_dequeue_soft( s64 credits; int len; + /* The previous packet is still being sent */ + if (now < q->last) { + qdisc_watchdog_schedule_ns(&q->watchdog, q->last); + return NULL; + } if (q->credits < 0) { credits = timediff_to_credits(now - q->last, q->idleslope); @@ -216,7 +221,12 @@ static struct sk_buff *cbs_dequeue_soft( credits += q->credits; q->credits = max_t(s64, credits, q->locredit); - q->last = now; + /* Estimate of the transmission of the last byte of the packet in ns */ + if (unlikely(atomic64_read(&q->port_rate) == 0)) + q->last = now; + else + q->last = now + div64_s64(len * NSEC_PER_SEC, + atomic64_read(&q->port_rate)); return skb; }