From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: Jens Freimann <jfreimann@redhat.com>, dev@dpdk.org
Cc: tiwei.bie@intel.com, Gavin.Hu@arm.com
Subject: Re: [dpdk-dev] [PATCH v11 0/9] implement packed virtqueues
Date: Mon, 3 Dec 2018 16:34:44 +0100 [thread overview]
Message-ID: <4d60bce7-7fb0-74bf-a1ac-a67b6275e513@redhat.com> (raw)
In-Reply-To: <20181203152925.sofjto3toduxlpd6@jenstp.localdomain>
On 12/3/18 4:29 PM, Jens Freimann wrote:
> On Mon, Dec 03, 2018 at 03:15:06PM +0100, Jens Freimann wrote:
>>
>> This is a basic implementation of packed virtqueues as specified in the
>> Virtio 1.1 draft. A compiled version of the current draft is available
>> at https://github.com/oasis-tcs/virtio-docs.git (or as .pdf at
>> https://github.com/oasis-tcs/virtio-docs/blob/master/virtio-v1.1-packed-wd10.pdf
>>
>>
>> A packed virtqueue is different from a split virtqueue in that it
>> consists of only a single descriptor ring that replaces available and
>> used ring, index and descriptor pointers.
>>
>> Each descriptor is readable and writable and has a flags field. These
>> flags
>> will mark if a descriptor is available or used. To detect new
>> available descriptors
>> even after the ring has wrapped, device and driver each have a
>> single-bit wrap counter that is flipped from 0 to 1 and vice versa
>> every time
>> the last descriptor in the ring is used/made available.
>>
>> With this patch set I see a slight performance drop compared to split
>> virtqueues. I tested according to
>> http://doc.dpdk.org/guides/howto/pvp_reference_benchmark.html and I see
>> a small performance drop of 3-4 percent in PVP and and similar numbers
>
> It's actually bigger with mergeable rx buffers turned off. I measured
> 13% less mpps with packed virtqueues.
That's interesting. I just tried Rxonly micro-benchmark, and I get
almost same perf for mrg and non-mrg cases:
MRG ON: 14.45Mpps
MRG OFF: 14.57Mpps
> regards,
> Jens
prev parent reply other threads:[~2018-12-03 15:34 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-03 14:15 Jens Freimann
2018-12-03 14:15 ` [dpdk-dev] [PATCH v11 1/9] net/virtio: vring init for packed queues Jens Freimann
2018-12-03 14:15 ` [dpdk-dev] [PATCH v11 2/9] net/virtio: add packed virtqueue defines Jens Freimann
2018-12-03 14:15 ` [dpdk-dev] [PATCH v11 3/9] net/virtio: add packed virtqueue helpers Jens Freimann
2018-12-05 11:27 ` Maxime Coquelin
2018-12-03 14:15 ` [dpdk-dev] [PATCH v11 4/9] net/virtio: dump packed virtqueue data Jens Freimann
2018-12-03 14:15 ` [dpdk-dev] [PATCH v11 5/9] net/virtio: implement transmit path for packed queues Jens Freimann
2018-12-05 11:16 ` Maxime Coquelin
2018-12-03 14:15 ` [dpdk-dev] [PATCH v11 6/9] net/virtio: implement receive " Jens Freimann
2018-12-05 11:28 ` Maxime Coquelin
2018-12-05 12:19 ` Jens Freimann
2018-12-05 22:52 ` Stephen Hemminger
2018-12-03 14:15 ` [dpdk-dev] [PATCH v11 7/9] net/virtio: add virtio send command packed queue support Jens Freimann
2018-12-03 14:15 ` [dpdk-dev] [PATCH v11 8/9] net/virtio-user: add option to use packed queues Jens Freimann
2018-12-03 14:15 ` [dpdk-dev] [PATCH v11 9/9] net/virtio: enable packed virtqueues by default Jens Freimann
2018-12-03 15:29 ` [dpdk-dev] [PATCH v11 0/9] implement packed virtqueues Jens Freimann
2018-12-03 15:34 ` Maxime Coquelin [this message]
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