From: Shirley Ma <mashirle@us•ibm.com>
To: Rusty Russell <rusty@rustcorp•com.au>
Cc: "Michael S. Tsirkin" <mst@redhat•com>,
netdev@vger•kernel.org, Herbert Xu <herbert@gondor•apana.org.au>
Subject: Re: [PATCH RFC] virtio_net: use NAPI for xmit (UNTESTED)
Date: Wed, 31 Mar 2010 00:13:21 -0700 [thread overview]
Message-ID: <1270019601.25337.7.camel@localhost.localdomain> (raw)
In-Reply-To: <201003311429.57793.rusty@rustcorp.com.au>
On Wed, 2010-03-31 at 14:29 +1030, Rusty Russell wrote:
> +static int virtnet_xmit_poll(struct napi_struct *xmit_napi, int
> budget)
> +{
> + struct virtnet_info *vi =
> + container_of(xmit_napi, struct virtnet_info,
> xmit_napi);
> +
> + /* Don't access vq/capacity at same time as start_xmit. */
> + __netif_tx_lock(netdev_get_tx_queue(vi->dev, 0),
> smp_processor_id());
> +
> + vi->capacity += free_old_xmit_skbs(vi);
> + if (vi->capacity >= 2 + MAX_SKB_FRAGS) {
> + /* Suppress further xmit interrupts. */
> + vi->svq->vq_ops->disable_cb(vi->svq);
> + napi_complete(xmit_napi);
> +
> + /* Don't wake it if link is down. */
> + if (likely(netif_carrier_ok(vi->vdev)))
This should be if (likely(netif_carrier_ok(vi->dev)))
> + netif_wake_queue(vi->dev);
> + }
> +
> + __netif_tx_unlock(netdev_get_tx_queue(vi->dev, 0));
> + return 1;
> +}
> +
I tested the backport patch with vhost on, the initial netperf test
result showed BW performance decreased 10% with same cpu utilization. I
will look at it tomorrow.
Shirley
prev parent reply other threads:[~2010-03-31 7:13 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-31 3:59 [PATCH RFC] virtio_net: use NAPI for xmit (UNTESTED) Rusty Russell
2010-03-31 5:44 ` Shirley Ma
2010-03-31 5:58 ` Shirley Ma
2010-03-31 7:13 ` Shirley Ma [this message]
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