From patchwork Thu Feb 5 06:14:00 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stephen Hemminger X-Patchwork-Id: 3002 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 A6CB9B438; Thu, 5 Feb 2015 07:14:21 +0100 (CET) Received: from mail-pd0-f177.google.com (mail-pd0-f177.google.com [209.85.192.177]) by dpdk.org (Postfix) with ESMTP id 619C7B41E for ; Thu, 5 Feb 2015 07:14:19 +0100 (CET) Received: by pdbnh10 with SMTP id nh10so3140825pdb.12 for ; Wed, 04 Feb 2015 22:14:18 -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=Vf2tGKvBJv6ZXs6Vzx6/nP73agQAuKNTfMEMNRoulsl+HcwE64gRZqIHCqvHeH3DtK ie6o0aTDp30B16IRTxg4awZBWchi0opPMAfNOiIeFKUY1vgCMRRP0toMLuJSWBtK/Sg1 k+aV/xVR05jp3f8SGEeQ/2wKPa1+oxgD2A9MavOd/R0td6Ud5++tB4qTacp14q0+nYN7 tc2qxqlOzB4ROiFSKFTKR1jkgMqH9lwl4BO5p+5GBmXEQOSaJ+T8gGBe7G/HaktkVVXH d6h+U//sCfj+OTASDDnxmletsmyYiGdfP4UvcVz+tVEl6M5xbjKPo3Nv3PhtJqTq13Lo K4dQ== X-Gm-Message-State: ALoCoQlPinLWC0zASJncGLCrwKk6AkFAx17VvI6jurD2Q6/2tY41x0h87jXL3Z3NFSU3KA0ceK2E X-Received: by 10.68.196.99 with SMTP id il3mr3268870pbc.158.1423116858704; Wed, 04 Feb 2015 22:14:18 -0800 (PST) Received: from urahara.brocade.com (static-50-53-82-155.bvtn.or.frontiernet.net. [50.53.82.155]) by mx.google.com with ESMTPSA id ib3sm3848178pbc.41.2015.02.04.22.14.17 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 04 Feb 2015 22:14:18 -0800 (PST) From: Stephen Hemminger To: dev@dpdk.org Date: Wed, 4 Feb 2015 22:14:00 -0800 Message-Id: <1423116841-19799-6-git-send-email-stephen@networkplumber.org> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1423116841-19799-4-git-send-email-stephen@networkplumber.org> References: <1423116841-19799-4-git-send-email-stephen@networkplumber.org> Cc: Stephen Hemminger Subject: [dpdk-dev] [PATCH v2 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; }