Michael S. Tsirkin
2021-Aug-30 21:10 UTC
[PATCH] virtio_net: reduce raw_smp_processor_id() calling in virtnet_xdp_get_sq
On Thu, Aug 26, 2021 at 04:21:35PM +0800, Li RongQing wrote:> smp_processor_id()/raw* will be called once each when not > more queues in virtnet_xdp_get_sq() which is called in > non-preemptible context, so it's safe to call the function > smp_processor_id() once. > > Signed-off-by: Li RongQing <lirongqing at baidu.com>commit log should probably explain why it's a good idea to replace raw_smp_processor_id with smp_processor_id in the case of curr_queue_pairs <= nr_cpu_ids.> --- > drivers/net/virtio_net.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 2e42210a6503..2a7b368c1da2 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -528,19 +528,20 @@ static int __virtnet_xdp_xmit_one(struct virtnet_info *vi, > * functions to perfectly solve these three problems at the same time. > */ > #define virtnet_xdp_get_sq(vi) ({ \ > + int cpu = smp_processor_id(); \ > struct netdev_queue *txq; \ > typeof(vi) v = (vi); \ > unsigned int qp; \ > \ > if (v->curr_queue_pairs > nr_cpu_ids) { \ > qp = v->curr_queue_pairs - v->xdp_queue_pairs; \ > - qp += smp_processor_id(); \ > + qp += cpu; \ > txq = netdev_get_tx_queue(v->dev, qp); \ > __netif_tx_acquire(txq); \ > } else { \ > - qp = smp_processor_id() % v->curr_queue_pairs; \ > + qp = cpu % v->curr_queue_pairs; \ > txq = netdev_get_tx_queue(v->dev, qp); \ > - __netif_tx_lock(txq, raw_smp_processor_id()); \ > + __netif_tx_lock(txq, cpu); \ > } \ > v->sq + qp; \ > }) > -- > 2.33.0.69.gc420321.dirty > >