From patchwork Sun Feb 1 10:03:50 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stephen Hemminger X-Patchwork-Id: 2890 Return-Path: X-Original-To: patchwork@dpdk.org Delivered-To: patchwork@dpdk.org Received: from [92.243.14.124] (localhost [IPv6:::1]) by dpdk.org (Postfix) with ESMTP id 80ED8376D; Sun, 1 Feb 2015 11:04:15 +0100 (CET) Received: from mail-la0-f47.google.com (mail-la0-f47.google.com [209.85.215.47]) by dpdk.org (Postfix) with ESMTP id 6A5D23208 for ; Sun, 1 Feb 2015 11:04:14 +0100 (CET) Received: by mail-la0-f47.google.com with SMTP id hz20so32726960lab.6 for ; Sun, 01 Feb 2015 02:04:14 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=iFIrImkxJq7G1PYW+yMIsbWmxquBv2YYAvdCOkI/o0M=; b=YQ5o7My8ObxDf2oHEHH+hSL01OO9wHlKuOmaABGoiPhOw4VEl8Hy6fC0/pQPlWMmdV 4n+KjTBGujf9X2NDw6Sdl8FML8mDqROZV72IjnMEm2b7oEQBcx+BMOuGO0Xs9IuMLVP2 I6m+K61t91cXfTl1UKK8KANNWPRjMIkA0i+WZ2d/gGW5Hqssb+/TA4WxrWWA0PzwvkSp cdqd5PKzSv3pUquWKDLAIFctlwngPlAHCDA6qNlyXCHcOibkkS0HJGNCi8wBL2RZQQb4 wBYYgnJnRU7vo0BMAz1o57jM98rlOBlI8zg7pWTJtwBaNsADtDNmM6ZWGNxTr6hJ+p/j NhEg== X-Gm-Message-State: ALoCoQm741MBJSON/CRaoOQCX+dUcfzz2CSPjUwIZBOZ0plZYTcAflwxH8VURCukrXNJKkgi1r7O X-Received: by 10.152.26.98 with SMTP id k2mr14499555lag.53.1422785054173; Sun, 01 Feb 2015 02:04:14 -0800 (PST) Received: from uryu.fosdem.net. ([2001:67c:1810:f0ff:c685:8ff:feca:841f]) by mx.google.com with ESMTPSA id c4sm1608100lbp.32.2015.02.01.02.04.12 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Sun, 01 Feb 2015 02:04:13 -0800 (PST) From: Stephen Hemminger To: dev@dpdk.org Date: Sun, 1 Feb 2015 10:03:50 +0000 Message-Id: <1422785031-11494-6-git-send-email-stephen@networkplumber.org> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1422785031-11494-1-git-send-email-stephen@networkplumber.org> References: <1422785031-11494-1-git-send-email-stephen@networkplumber.org> Cc: Stephen Hemminger Subject: [dpdk-dev] [PATCH 6/7] rte_sched: eliminate floating point in calculating byte clock X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" From: Stephen Hemminger The old code was doing a floating point divide for each rte_dequeue() which is very expensive. Change to using fixed point scaled math instead. This improved performance from 5Gbit/sec to 10 Gbit/sec Signed-off-by: Stephen Hemminger --- lib/librte_sched/rte_sched.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/lib/librte_sched/rte_sched.c b/lib/librte_sched/rte_sched.c index 55fbc14..3023457 100644 --- a/lib/librte_sched/rte_sched.c +++ b/lib/librte_sched/rte_sched.c @@ -102,6 +102,9 @@ #define RTE_SCHED_BMP_POS_INVALID UINT32_MAX +/* For cycles_per_byte calculation */ +#define RTE_SCHED_TIME_SHIFT 20 + struct rte_sched_subport { /* Token bucket (TB) */ uint64_t tb_time; /* time of last update */ @@ -239,7 +242,7 @@ struct rte_sched_port { uint64_t time_cpu_cycles; /* Current CPU time measured in CPU cyles */ uint64_t time_cpu_bytes; /* Current CPU time measured in bytes */ uint64_t time; /* Current NIC TX time measured in bytes */ - double cycles_per_byte; /* CPU cycles per byte */ + uint32_t cycles_per_byte; /* CPU cycles per byte (scaled) */ /* Scheduling loop detection */ uint32_t pipe_loop; @@ -657,7 +660,9 @@ rte_sched_port_config(struct rte_sched_port_params *params) port->time_cpu_cycles = rte_get_tsc_cycles(); port->time_cpu_bytes = 0; port->time = 0; - port->cycles_per_byte = ((double) rte_get_tsc_hz()) / ((double) params->rate); + + port->cycles_per_byte = (rte_get_tsc_hz() << RTE_SCHED_TIME_SHIFT) + / params->rate; /* Scheduling loop detection */ port->pipe_loop = RTE_SCHED_PIPE_INVALID; @@ -2156,11 +2161,12 @@ rte_sched_port_time_resync(struct rte_sched_port *port) { uint64_t cycles = rte_get_tsc_cycles(); uint64_t cycles_diff = cycles - port->time_cpu_cycles; - double bytes_diff = ((double) cycles_diff) / port->cycles_per_byte; + uint64_t bytes_diff = (cycles_diff << RTE_SCHED_TIME_SHIFT) + / port->cycles_per_byte; /* Advance port time */ port->time_cpu_cycles = cycles; - port->time_cpu_bytes += (uint64_t) bytes_diff; + port->time_cpu_bytes += bytes_diff; if (port->time < port->time_cpu_bytes) { port->time = port->time_cpu_bytes; }