From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (xvm-189-124.dc0.ghst.net [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 0F592A0524; Thu, 7 Jan 2021 17:35:59 +0100 (CET) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id B30B1140F74; Thu, 7 Jan 2021 17:35:58 +0100 (CET) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [63.128.21.124]) by mails.dpdk.org (Postfix) with ESMTP id 5BB82140DF7 for ; Thu, 7 Jan 2021 17:35:57 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1610037356; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vGVwTU4bsKvdRkujiedIRby1yGXaup2BohrK57fbvfE=; b=av7TcN5gY2CJtQ18glqWc5SrK/h55p9bnk0i1o72/xhNndSS8Ky0frYbXdCmRhl08OcJSc T55sIELhL7aMuZs1vWSqnJ9+aLSKK/a82WWfOXifOy1pdgbj/4t/sNeLRSMJOKdE82714U WeSEyJAOKl7wrwLN4OYeIxtdjQSUa4M= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-226-xMjEq3N9P-yyg7ATlvc3yw-1; Thu, 07 Jan 2021 11:35:41 -0500 X-MC-Unique: xMjEq3N9P-yyg7ATlvc3yw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id F311E835E06; Thu, 7 Jan 2021 16:35:38 +0000 (UTC) Received: from [10.36.110.9] (unknown [10.36.110.9]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 65EEE5C67A; Thu, 7 Jan 2021 16:35:37 +0000 (UTC) To: Joyce Kong , chenbo.xia@intel.com, honnappa.nagarahalli@arm.com, ruifeng.wang@arm.com Cc: dev@dpdk.org, nd@arm.com References: <20201221155033.6771-1-joyce.kong@arm.com> <20201221155033.6771-3-joyce.kong@arm.com> From: Maxime Coquelin Message-ID: <69c1223d-8336-deb3-addd-2eed27e684f1@redhat.com> Date: Thu, 7 Jan 2021 17:35:35 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20201221155033.6771-3-joyce.kong@arm.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=maxime.coquelin@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] [PATCH v1 2/8] examples/vhost_blk: replace smp with thread fence X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 12/21/20 4:50 PM, Joyce Kong wrote: > Simply replace the rte_smp_mb barriers with SEQ_CST atomic thread fence, > if there is no load/store operations. > > Signed-off-by: Joyce Kong > Reviewed-by: Ruifeng Wang > --- > examples/vhost_blk/vhost_blk.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/examples/vhost_blk/vhost_blk.c b/examples/vhost_blk/vhost_blk.c > index bb293d492..7ea60863d 100644 > --- a/examples/vhost_blk/vhost_blk.c > +++ b/examples/vhost_blk/vhost_blk.c > @@ -86,9 +86,9 @@ enqueue_task(struct vhost_blk_task *task) > */ > used->ring[used->idx & (vq->vring.size - 1)].id = task->req_idx; > used->ring[used->idx & (vq->vring.size - 1)].len = task->data_len; >From here > - rte_smp_mb(); > + rte_atomic_thread_fence(__ATOMIC_SEQ_CST); > used->idx++; > - rte_smp_mb(); > + rte_atomic_thread_fence(__ATOMIC_SEQ_CST); to here, couldn't it be replaced with: __atomic_add_fetch(&used->idx, 1, __ATOMIC_RELEASE); ? > rte_vhost_clr_inflight_desc_split(task->ctrlr->vid, > vq->id, used->idx, task->req_idx); > @@ -112,12 +112,12 @@ enqueue_task_packed(struct vhost_blk_task *task) > desc->id = task->buffer_id; > desc->addr = 0; > > - rte_smp_mb(); > + rte_atomic_thread_fence(__ATOMIC_SEQ_CST); > if (vq->used_wrap_counter) > desc->flags |= VIRTQ_DESC_F_AVAIL | VIRTQ_DESC_F_USED; > else > desc->flags &= ~(VIRTQ_DESC_F_AVAIL | VIRTQ_DESC_F_USED); > - rte_smp_mb(); > + rte_atomic_thread_fence(__ATOMIC_SEQ_CST); > > rte_vhost_clr_inflight_desc_packed(task->ctrlr->vid, vq->id, > task->inflight_idx); >