From: "Tan, Jianfeng" <jianfeng.tan@intel.com>
To: Rich Lane <rich.lane@bigswitch.com>, dev@dpdk.org
Cc: Huawei Xie <huawei.xie@intel.com>,
Yuanhan Liu <yuanhan.liu@linux.intel.com>,
Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: [dpdk-dev] [PATCH v2] virtio: use zeroed memory for simple TX header
Date: Tue, 5 Apr 2016 11:20:05 +0800 [thread overview]
Message-ID: <57032EE5.4050408@intel.com> (raw)
In-Reply-To: <1459822261-95284-1-git-send-email-rlane@bigswitch.com>
Hi,
On 4/5/2016 10:11 AM, Rich Lane wrote:
> For simple TX the virtio-net header must be zeroed, but it was using memory
> that had been initialized with indirect descriptor tables. This resulted in
> "unsupported gso type" errors from librte_vhost.
>
> We can use the same memory for every descriptor to save cachelines in the
> vswitch.
Pointing all virtio_net_hdr into the same memory may brings performance,
but how much? It also introduces difficulty to adding tso in future?
Thanks,
Jianfeng
>
> Fixes: 6dc5de3a (virtio: use indirect ring elements)
> Signed-off-by: Rich Lane <rlane@bigswitch.com>
> ---
> v1-v2:
> - Use offsetof to get address of tx_hdr
>
> drivers/net/virtio/virtio_rxtx.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/virtio/virtio_rxtx.c b/drivers/net/virtio/virtio_rxtx.c
> index 2b88efd..ef21d8e 100644
> --- a/drivers/net/virtio/virtio_rxtx.c
> +++ b/drivers/net/virtio/virtio_rxtx.c
> @@ -377,7 +377,7 @@ virtio_dev_vring_start(struct virtqueue *vq, int queue_type)
> vq->vq_ring.desc[i + mid_idx].next = i;
> vq->vq_ring.desc[i + mid_idx].addr =
> vq->virtio_net_hdr_mem +
> - i * vq->hw->vtnet_hdr_size;
> + offsetof(struct virtio_tx_region, tx_hdr);
> vq->vq_ring.desc[i + mid_idx].len =
> vq->hw->vtnet_hdr_size;
> vq->vq_ring.desc[i + mid_idx].flags =
next prev parent reply other threads:[~2016-04-05 3:20 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-05 2:11 Rich Lane
2016-04-05 3:20 ` Tan, Jianfeng [this message]
2016-04-05 4:26 ` Yuanhan Liu
2016-04-05 5:34 ` Tan, Jianfeng
2016-04-05 4:25 ` Yuanhan Liu
2016-04-06 10:28 ` Thomas Monjalon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=57032EE5.4050408@intel.com \
--to=jianfeng.tan@intel.com \
--cc=dev@dpdk.org \
--cc=huawei.xie@intel.com \
--cc=rich.lane@bigswitch.com \
--cc=stephen@networkplumber.org \
--cc=yuanhan.liu@linux.intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).