From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by dpdk.org (Postfix) with ESMTP id 73DB61B28E for ; Thu, 7 Jun 2018 16:38:42 +0200 (CEST) Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 030E3401DEC2; Thu, 7 Jun 2018 14:38:42 +0000 (UTC) Received: from localhost.localdomain (ovpn-112-46.ams2.redhat.com [10.36.112.46]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2B77410EE6C5; Thu, 7 Jun 2018 14:38:37 +0000 (UTC) From: Maxime Coquelin To: zhihong.wang@intel.com, tiwei.bie@intel.com, dev@dpdk.org Cc: Maxime Coquelin Date: Thu, 7 Jun 2018 16:38:26 +0200 Message-Id: <20180607143826.23647-1-maxime.coquelin@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Thu, 07 Jun 2018 14:38:42 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Thu, 07 Jun 2018 14:38:42 +0000 (UTC) for IP:'10.11.54.3' DOMAIN:'int-mx03.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'maxime.coquelin@redhat.com' RCPT:'' Subject: [dpdk-dev] [PATCH] vhost: use SMP memory barrier before kicking guest X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 07 Jun 2018 14:38:42 -0000 vhost_vring_call() used rte_mb(), which translates into mfence instruction on x86. This patch changes to use rte_smp_mb(), which changed recently to translate into a locked ADD instruction for performance reason. The measured gain is up to 3% with the testpmd benchmarks. Signed-off-by: Maxime Coquelin --- lib/librte_vhost/vhost.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h index 58c425a5c..1bc99ed3c 100644 --- a/lib/librte_vhost/vhost.h +++ b/lib/librte_vhost/vhost.h @@ -591,7 +591,7 @@ static __rte_always_inline void vhost_vring_call(struct virtio_net *dev, struct vhost_virtqueue *vq) { /* Flush used->idx update before we read avail->flags. */ - rte_mb(); + rte_smp_mb(); /* Don't kick guest if we don't reach index specified by guest. */ if (dev->features & (1ULL << VIRTIO_RING_F_EVENT_IDX)) { -- 2.14.3