From: Kevin Traynor <ktraynor@redhat.com>
To: Bruce Richardson <bruce.richardson@intel.com>
Cc: Zhiyong Yang <zhiyong.yang@intel.com>,
dev@dpdk.org, yuanhan.liu@linux.intel.com,
maxime.coquelin@redhat.com
Subject: Re: [dpdk-dev] [PATCH 4/5] net/vhost: remove limit of vhost TX burst size
Date: Fri, 24 Feb 2017 13:33:28 +0000 [thread overview]
Message-ID: <413fb2ba-9d36-7403-8e74-7cd4af814d9f@redhat.com> (raw)
In-Reply-To: <20170224130429.GA88332@bricha3-MOBL3.ger.corp.intel.com>
On 02/24/2017 01:04 PM, Bruce Richardson wrote:
> On Fri, Feb 24, 2017 at 11:08:56AM +0000, Kevin Traynor wrote:
>> On 02/24/2017 08:48 AM, Zhiyong Yang wrote:
>>> vhost removes limit of TX burst size(32 pkts) and supports to make
>>> an best effort to transmit pkts.
>>>
>>> Cc: yuanhan.liu@linux.intel.com
>>> Cc: maxime.coquelin@redhat.com
>>>
>>> Signed-off-by: Zhiyong Yang <zhiyong.yang@intel.com>
>>> ---
>>> drivers/net/vhost/rte_eth_vhost.c | 24 ++++++++++++++++++++++--
>>> 1 file changed, 22 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/net/vhost/rte_eth_vhost.c b/drivers/net/vhost/rte_eth_vhost.c
>>> index e98cffd..1e1fa34 100644
>>> --- a/drivers/net/vhost/rte_eth_vhost.c
>>> +++ b/drivers/net/vhost/rte_eth_vhost.c
>>> @@ -52,6 +52,7 @@
>>> #define ETH_VHOST_QUEUES_ARG "queues"
>>> #define ETH_VHOST_CLIENT_ARG "client"
>>> #define ETH_VHOST_DEQUEUE_ZERO_COPY "dequeue-zero-copy"
>>> +#define VHOST_MAX_PKT_BURST 32
>>>
>>> static const char *valid_arguments[] = {
>>> ETH_VHOST_IFACE_ARG,
>>> @@ -434,8 +435,27 @@ eth_vhost_tx(void *q, struct rte_mbuf **bufs, uint16_t nb_bufs)
>>> goto out;
>>>
>>> /* Enqueue packets to guest RX queue */
>>> - nb_tx = rte_vhost_enqueue_burst(r->vid,
>>> - r->virtqueue_id, bufs, nb_bufs);
>>> + if (likely(nb_bufs <= VHOST_MAX_PKT_BURST))
>>> + nb_tx = rte_vhost_enqueue_burst(r->vid, r->virtqueue_id,
>>> + bufs, nb_bufs);
>>> + else {
>>> + uint16_t nb_send = nb_bufs;
>>> +
>>> + while (nb_send) {
>>> + uint16_t nb_pkts;
>>> + uint16_t num = (uint16_t)RTE_MIN(nb_send,
>>> + VHOST_MAX_PKT_BURST);
>>> +
>>> + nb_pkts = rte_vhost_enqueue_burst(r->vid,
>>> + r->virtqueue_id,
>>> + &bufs[nb_tx], num);
>>> +
>>> + nb_tx += nb_pkts;
>>> + nb_send -= nb_pkts;
>>> + if (nb_pkts < num)
>>> + break;
>>> + }
>>
>> In the code above,
>> - if the VM does not service the queue, this will spin forever
> I don't think that is the case. As soon as the enqueue stops sending a
> full burst of (presumably 32) pkts, it will hit the break condition and
> quit. If it does send the full burst, it makes good forward progress
> until it runs out of packets to send and then quits.
>
>> - if the queue is almost full, it will be very slow
> Again, should not be the case. As soon as a full burst is not full
> enqueued the logic quits the loop.
>
My bad - you are of course correct. In that case it makes sense, as the
retries are just enough to allow all packets a chance to be sent but not
to retry when packets fail to send.
thanks,
Kevin.
> /Bruce
>
next prev parent reply other threads:[~2017-02-24 13:33 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-24 8:48 [dpdk-dev] [PATCH 0/5] consistent PMD batching behaviour Zhiyong Yang
2017-02-24 8:48 ` [dpdk-dev] [PATCH 1/5] net/fm10k: remove limit of fm10k_xmit_pkts_vec burst size Zhiyong Yang
2017-02-24 9:32 ` Bruce Richardson
2017-02-24 9:36 ` Bruce Richardson
2017-02-24 9:48 ` Yang, Zhiyong
2017-03-03 11:17 ` [dpdk-dev] [PATCH v2 0/5] consistent PMD batching behaviour Zhiyong Yang
2017-03-03 11:17 ` [dpdk-dev] [PATCH v2 1/5] net/fm10k: remove limit of fm10k_xmit_pkts_vec burst size Zhiyong Yang
2017-03-29 7:16 ` [dpdk-dev] [PATCH v3 0/5] consistent PMD batching behaviour Zhiyong Yang
2017-03-29 7:16 ` [dpdk-dev] [PATCH v3 1/5] net/fm10k: remove limit of fm10k_xmit_pkts_vec burst size Zhiyong Yang
2017-03-29 7:16 ` [dpdk-dev] [PATCH v3 2/5] net/i40e: remove limit of i40e_xmit_pkts_vec " Zhiyong Yang
2017-03-29 7:16 ` [dpdk-dev] [PATCH v3 3/5] net/ixgbe: remove limit of ixgbe_xmit_pkts_vec " Zhiyong Yang
2017-03-29 7:16 ` [dpdk-dev] [PATCH v3 4/5] net/vhost: remove limit of vhost TX " Zhiyong Yang
2017-03-29 7:16 ` [dpdk-dev] [PATCH v3 5/5] net/vhost: remove limit of vhost RX " Zhiyong Yang
2017-03-30 12:54 ` [dpdk-dev] [PATCH v3 0/5] consistent PMD batching behaviour Ferruh Yigit
2017-03-31 7:00 ` Yao, Lei A
2017-03-03 11:17 ` [dpdk-dev] [PATCH v2 2/5] net/i40e: remove limit of i40e_xmit_pkts_vec burst size Zhiyong Yang
2017-03-24 14:03 ` Ferruh Yigit
2017-03-03 11:17 ` [dpdk-dev] [PATCH v2 3/5] net/ixgbe: remove limit of ixgbe_xmit_pkts_vec " Zhiyong Yang
2017-03-03 11:17 ` [dpdk-dev] [PATCH v2 4/5] net/vhost: remove limit of vhost TX " Zhiyong Yang
2017-03-03 11:17 ` [dpdk-dev] [PATCH v2 5/5] net/vhost: remove limit of vhost RX " Zhiyong Yang
2017-03-05 13:02 ` [dpdk-dev] [PATCH v2 0/5] consistent PMD batching behaviour Ananyev, Konstantin
2017-03-06 2:13 ` Yang, Zhiyong
2017-03-24 14:02 ` Ferruh Yigit
2017-03-25 6:29 ` Yang, Zhiyong
2017-03-28 10:00 ` Yang, Zhiyong
2017-03-28 10:05 ` Ferruh Yigit
2017-02-24 8:48 ` [dpdk-dev] [PATCH 2/5] net/i40e: remove limit of i40e_xmit_pkts_vec burst size Zhiyong Yang
2017-02-24 8:48 ` [dpdk-dev] [PATCH 3/5] net/ixgbe: remove limit of ixgbe_xmit_pkts_vec " Zhiyong Yang
2017-02-24 8:48 ` [dpdk-dev] [PATCH 4/5] net/vhost: remove limit of vhost TX " Zhiyong Yang
2017-02-24 11:08 ` Kevin Traynor
2017-02-24 13:04 ` Bruce Richardson
2017-02-24 13:33 ` Kevin Traynor [this message]
2017-03-01 9:44 ` Maxime Coquelin
2017-03-01 13:24 ` Yang, Zhiyong
2017-02-24 8:48 ` [dpdk-dev] [PATCH 5/5] net/vhost: remove limit of vhost RX " Zhiyong Yang
2017-02-24 11:41 ` Kevin Traynor
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