From: Maxime Coquelin <maxime.coquelin@redhat.com> To: Joyce Kong <joyce.kong@arm.com>, chenbo.xia@intel.com, honnappa.nagarahalli@arm.com, ruifeng.wang@arm.com Cc: dev@dpdk.org, nd@arm.com Subject: Re: [dpdk-dev] [PATCH v1 2/8] examples/vhost_blk: replace smp with thread fence Date: Thu, 7 Jan 2021 17:35:35 +0100 Message-ID: <69c1223d-8336-deb3-addd-2eed27e684f1@redhat.com> (raw) In-Reply-To: <20201221155033.6771-3-joyce.kong@arm.com> 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 <joyce.kong@arm.com> > Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com> > --- > 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); >
next prev parent reply other threads:[~2021-01-07 16:35 UTC|newest] Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-12-21 15:50 [dpdk-dev] [PATCH v1 0/8] replace smp barriers in vhost with C11 atomic Joyce Kong 2020-12-21 15:50 ` [dpdk-dev] [PATCH v1 1/8] examples/vhost: relax memory ordering when enqueue/dequeue Joyce Kong 2021-01-07 16:33 ` Maxime Coquelin 2020-12-21 15:50 ` [dpdk-dev] [PATCH v1 2/8] examples/vhost_blk: replace smp with thread fence Joyce Kong 2021-01-07 16:35 ` Maxime Coquelin [this message] 2020-12-21 15:50 ` [dpdk-dev] [PATCH v1 3/8] vhost: remove unnecessary smp barrier for desc flags Joyce Kong 2021-01-07 16:38 ` Maxime Coquelin 2020-12-21 15:50 ` [dpdk-dev] [PATCH v1 4/8] vhost: remove unnecessary smp barrier for avail idx Joyce Kong 2021-01-07 16:43 ` Maxime Coquelin 2020-12-21 15:50 ` [dpdk-dev] [PATCH v1 5/8] vhost: relax full barriers for desc flags Joyce Kong 2021-01-07 16:45 ` Maxime Coquelin 2020-12-21 15:50 ` [dpdk-dev] [PATCH v1 6/8] vhost: relax full barriers for used idx Joyce Kong 2021-01-07 16:46 ` Maxime Coquelin 2020-12-21 15:50 ` [dpdk-dev] [PATCH v1 7/8] vhost: replace smp with thread fence for packed vring Joyce Kong 2021-01-07 17:06 ` Maxime Coquelin 2020-12-21 15:50 ` [dpdk-dev] [PATCH v1 8/8] vhost: replace smp with thread fence for control path Joyce Kong 2021-01-07 17:15 ` Maxime Coquelin 2021-01-08 9:16 ` [dpdk-dev] [PATCH v1 0/8] replace smp barriers in vhost with C11 atomic Maxime Coquelin
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