From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dor Laor Subject: [Virtio-for-kvm] [PATCH 10/13] [Mostly resend] virtio additions Date: Fri, 21 Dec 2007 17:26:08 +0200 Message-ID: <476BDB10.7090006@qumranet.com> Reply-To: dor.laor-atKUWr5tajBWk0Htik3J/w@public.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: kvm-devel , virtualization , Rusty Russell , Anthony Liguori , Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org From 7354db58f496b06369e57d9be87e9c84db087690 Mon Sep 17 00:00:00 2001 From: Dor Laor Date: Wed, 12 Dec 2007 14:52:00 +0200 Subject: [PATCH] Don't arm tx hrtimer with a constant 500us each transmit The current start_xmit sets 500us hrtimer to kick the host. The problem is that if another xmit happens before the timer was fired then the first xmit will have to wait additional 500us. This patch does not re-arm the timer if there is existing one. This will shorten the latency for tx. It improves tx throughput by 20% Signed-off-by: Dor Laor --- drivers/net/virtio_net.c | 8 ++++---- 1 files changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 538cc37..0403d65 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -392,10 +392,10 @@ again: vi->stats.sendq_kicks++; vi->svq->vq_ops->kick(vi->svq); vi->out_num = 0; - } else { - vi->stats.hrtimer_starts++; - hrtimer_start(&vi->tx_timer, ktime_set(0,500000), - HRTIMER_MODE_REL); + } else if (!hrtimer_is_queued(&vi->tx_timer)) { + vi->stats.hrtimer_starts++; + hrtimer_start(&vi->tx_timer, ktime_set(0,500000), + HRTIMER_MODE_REL); } return 0; } -- 1.5.3.3 ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/