From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: Tiwei Bie <tiwei.bie@intel.com>, zhihong.wang@intel.com, dev@dpdk.org
Cc: stable@dpdk.org
Subject: Re: [dpdk-stable] [PATCH 2/5] net/virtio: fix in-order Tx path for split ring
Date: Thu, 21 Feb 2019 12:08:08 +0100 [thread overview]
Message-ID: <cd16f1e8-f77a-d9be-2910-986dac062ad0@redhat.com> (raw)
In-Reply-To: <20190219105951.31046-3-tiwei.bie@intel.com>
On 2/19/19 11:59 AM, Tiwei Bie wrote:
> When IN_ORDER feature is negotiated, device may just write out a
> single used ring entry for a batch of buffers:
>
> """
> Some devices always use descriptors in the same order in which they
> have been made available. These devices can offer the VIRTIO_F_IN_ORDER
> feature. If negotiated, this knowledge allows devices to notify the
> use of a batch of buffers to the driver by only writing out a single
> used ring entry with the id corresponding to the head entry of the
> descriptor chain describing the last buffer in the batch.
>
> The device then skips forward in the ring according to the size of
> the batch. Accordingly, it increments the used idx by the size of
> the batch.
>
> The driver needs to look up the used id and calculate the batch size
> to be able to advance to where the next used ring entry will be written
> by the device.
> """
>
> Currently, the in-order Tx path in split ring can't handle this.
> With this patch, driver will allocate desc_extra[] based on the
> index in avail/used ring instead of the index in descriptor table.
> And driver can just relay on the used->idx written by device to
> reclaim the descriptors and Tx buffers.
>
> Fixes: e5f456a98d3c ("net/virtio: support in-order Rx and Tx")
> Cc: stable@dpdk.org
>
> Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
> ---
> drivers/net/virtio/virtio_rxtx.c | 28 ++++++++++------------------
> 1 file changed, 10 insertions(+), 18 deletions(-)
>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Thanks,
Maxime
next prev parent reply other threads:[~2019-02-21 11:08 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190219105951.31046-1-tiwei.bie@intel.com>
2019-02-19 10:59 ` [dpdk-stable] [PATCH 1/5] net/virtio: fix Tx desc cleanup for packed ring Tiwei Bie
2019-02-21 11:05 ` Maxime Coquelin
2019-02-19 10:59 ` [dpdk-stable] [PATCH 2/5] net/virtio: fix in-order Tx path for split ring Tiwei Bie
2019-02-21 11:08 ` Maxime Coquelin [this message]
2019-02-19 10:59 ` [dpdk-stable] [PATCH 3/5] net/virtio: fix in-order Tx path for packed ring Tiwei Bie
2019-02-21 11:16 ` Maxime Coquelin
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