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Thu, 02 Mar 2023 09:47:47 -0500 X-MC-Unique: 4N-irg1sPXy_EZXwylRWeg-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id B011D280048F; Thu, 2 Mar 2023 14:47:46 +0000 (UTC) Received: from [10.39.208.28] (unknown [10.39.208.28]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CA2EF492C3E; Thu, 2 Mar 2023 14:47:45 +0000 (UTC) Message-ID: <5102a58b-cb5a-9ceb-c03d-925b294404c0@redhat.com> Date: Thu, 2 Mar 2023 15:47:44 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH 07/17] examples/vhost: use previous value atomic fetch operations To: Tyler Retzlaff , dev@dpdk.org Cc: Honnappa.Nagarahalli@arm.com, thomas@monjalon.net References: <1677718068-2412-1-git-send-email-roretzla@linux.microsoft.com> <1677718068-2412-8-git-send-email-roretzla@linux.microsoft.com> From: Maxime Coquelin In-Reply-To: <1677718068-2412-8-git-send-email-roretzla@linux.microsoft.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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 On 3/2/23 01:47, Tyler Retzlaff wrote: > Use __atomic_fetch_{add,and,or,sub,xor} instead of > __atomic_{add,and,or,sub,xor}_fetch when we have no interest in the > result of the operation. > > Reduces unnecessary codegen that provided the result of the atomic > operation that was not used. > > Change brings closer alignment with atomics available in C11 standard > and will reduce review effort when they are integrated. > > Signed-off-by: Tyler Retzlaff > --- > examples/vhost/main.c | 12 ++++++------ > examples/vhost/virtio_net.c | 4 ++-- > 2 files changed, 8 insertions(+), 8 deletions(-) > > diff --git a/examples/vhost/main.c b/examples/vhost/main.c > index 42e53a0..bfe466f 100644 > --- a/examples/vhost/main.c > +++ b/examples/vhost/main.c > @@ -1048,9 +1048,9 @@ static unsigned check_ports_num(unsigned nb_ports) > } > > if (enable_stats) { > - __atomic_add_fetch(&dst_vdev->stats.rx_total_atomic, 1, > + __atomic_fetch_add(&dst_vdev->stats.rx_total_atomic, 1, > __ATOMIC_SEQ_CST); > - __atomic_add_fetch(&dst_vdev->stats.rx_atomic, ret, > + __atomic_fetch_add(&dst_vdev->stats.rx_atomic, ret, > __ATOMIC_SEQ_CST); > src_vdev->stats.tx_total++; > src_vdev->stats.tx += ret; > @@ -1068,9 +1068,9 @@ static unsigned check_ports_num(unsigned nb_ports) > ret = vdev_queue_ops[vdev->vid].enqueue_pkt_burst(vdev, VIRTIO_RXQ, m, nr_xmit); > > if (enable_stats) { > - __atomic_add_fetch(&vdev->stats.rx_total_atomic, nr_xmit, > + __atomic_fetch_add(&vdev->stats.rx_total_atomic, nr_xmit, > __ATOMIC_SEQ_CST); > - __atomic_add_fetch(&vdev->stats.rx_atomic, ret, > + __atomic_fetch_add(&vdev->stats.rx_atomic, ret, > __ATOMIC_SEQ_CST); > } > > @@ -1400,9 +1400,9 @@ static void virtio_tx_offload(struct rte_mbuf *m) > } > > if (enable_stats) { > - __atomic_add_fetch(&vdev->stats.rx_total_atomic, rx_count, > + __atomic_fetch_add(&vdev->stats.rx_total_atomic, rx_count, > __ATOMIC_SEQ_CST); > - __atomic_add_fetch(&vdev->stats.rx_atomic, enqueue_count, > + __atomic_fetch_add(&vdev->stats.rx_atomic, enqueue_count, > __ATOMIC_SEQ_CST); > } > > diff --git a/examples/vhost/virtio_net.c b/examples/vhost/virtio_net.c > index 1d4737f..514c8e0 100644 > --- a/examples/vhost/virtio_net.c > +++ b/examples/vhost/virtio_net.c > @@ -231,7 +231,7 @@ > rte_prefetch0(&vr->desc[desc_indexes[i+1]]); > } > > - __atomic_add_fetch(&vr->used->idx, count, __ATOMIC_RELEASE); > + __atomic_fetch_add(&vr->used->idx, count, __ATOMIC_RELEASE); > queue->last_used_idx += count; > > rte_vhost_vring_call(dev->vid, queue_id); > @@ -442,7 +442,7 @@ > queue->last_avail_idx += i; > queue->last_used_idx += i; > > - __atomic_add_fetch(&vr->used->idx, i, __ATOMIC_ACQ_REL); > + __atomic_fetch_add(&vr->used->idx, i, __ATOMIC_ACQ_REL); > > rte_vhost_vring_call(dev->vid, queue_id); > Reviewed-by: Maxime Coquelin Thanks, Maxime