From: Jens Freimann <jfreimann@redhat.com>
To: Tiwei Bie <tiwei.bie@intel.com>
Cc: dev@dpdk.org, maxime.coquelin@redhat.com, Gavin.Hu@arm.com,
zhihong.wang@intel.com
Subject: Re: [dpdk-dev] [PATCH v6 00/11] implement packed virtqueues
Date: Fri, 21 Sep 2018 16:06:44 +0200 [thread overview]
Message-ID: <20180921140644.oiwl7gwekreflc7v@jenstp.localdomain> (raw)
In-Reply-To: <20180921123222.GA25292@debian>
On Fri, Sep 21, 2018 at 08:32:22PM +0800, Tiwei Bie wrote:
>On Fri, Sep 21, 2018 at 12:32:57PM +0200, 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 buffer.
>>
>> 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.
>>
>> The idea behind this is to 1. improve performance by avoiding cache misses
>> and 2. be easier for devices to implement.
>>
>> Regarding performance: with these patches I get 21.13 Mpps on my system
>> as compared to 18.8 Mpps with the virtio 1.0 code. Packet size was 64
>
>Did you enable multiple-queue and use multiple cores on
>vhost side? If not, I guess the above performance gain
>is the gain in vhost side instead of virtio side.
I tested several variations back then and they all looked very good.
But code change a lot meanwhile and I need to do more benchmarking
in any case.
>
>If you use more cores on vhost side or virtio side, will
>you see any performance changes?
>
>Did you do any performance test with the kernel vhost-net
>backend (with zero-copy enabled and disabled)? I think we
>also need some performance data for these two cases. And
>it can help us to make sure that it works with the kernel
>backends.
I tested against vhost-kernel but only to test functionality not
to benchmark.
>
>And for the "virtio-PMD + vhost-PMD" test cases, I think
>we need below performance data:
>
>#1. The maximum 1 core performance of virtio PMD when using split ring.
>#2. The maximum 1 core performance of virtio PMD when using packed ring.
>#3. The maximum 1 core performance of vhost PMD when using split ring.
>#4. The maximum 1 core performance of vhost PMD when using packed ring.
>
>And then we can have a clear understanding of the
>performance gain in DPDK with packed ring.
>
>And FYI, the maximum 1 core performance of virtio PMD
>can be got in below steps:
>
>1. Launch vhost-PMD with multiple queues, and use multiple
> CPU cores for forwarding.
>2. Launch virtio-PMD with multiple queues and use 1 CPU
> core for forwarding.
>3. Repeat above two steps with adding more CPU cores
> for forwarding in vhost-PMD side until we can't see
> performance increase anymore.
Thanks for the suggestions, I'll come back with more
numbers.
>
>Besides, I just did a quick glance at the Tx implementation,
>it still assumes the descs will be written back in order
>by device. You can find more details from my comments on
>that patch.
Saw it and noted. I had hoped to be able to avoid the list but
I see no way around it now.
Thanks for your review Tiwei!
regards,
Jens
prev parent reply other threads:[~2018-09-21 14:06 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-21 10:32 Jens Freimann
2018-09-21 10:32 ` [dpdk-dev] [PATCH v6 01/11] net/virtio: vring init for packed queues Jens Freimann
2018-09-21 10:32 ` [dpdk-dev] [PATCH v6 02/11] net/virtio: add packed virtqueue defines Jens Freimann
2018-09-21 10:33 ` [dpdk-dev] [PATCH v6 03/11] net/virtio: add packed virtqueue helpers Jens Freimann
2018-09-21 10:33 ` [dpdk-dev] [PATCH v6 04/11] net/virtio: flush packed receive virtqueues Jens Freimann
2018-09-21 10:33 ` [dpdk-dev] [PATCH v6 05/11] net/virtio: dump packed virtqueue data Jens Freimann
2018-09-21 10:33 ` [dpdk-dev] [PATCH v6 06/11] net/virtio: implement transmit path for packed queues Jens Freimann
2018-09-21 12:26 ` Tiwei Bie
2018-09-21 12:37 ` Jens Freimann
2018-09-21 12:49 ` Tiwei Bie
2018-09-21 10:33 ` [dpdk-dev] [PATCH v6 07/11] net/virtio: implement receive " Jens Freimann
2018-09-21 10:33 ` [dpdk-dev] [PATCH v6 08/11] net/virtio: add support for mergeable buffers with packed virtqueues Jens Freimann
2018-09-21 10:33 ` [dpdk-dev] [PATCH v6 09/11] net/virtio: add virtio send command packed queue support Jens Freimann
2018-09-21 12:37 ` Tiwei Bie
2018-09-21 10:33 ` [dpdk-dev] [PATCH v6 10/11] net/virtio-user: add option to use packed queues Jens Freimann
2018-09-21 10:33 ` [dpdk-dev] [PATCH v6 11/11] net/virtio: enable packed virtqueues by default Jens Freimann
2018-09-21 12:32 ` [dpdk-dev] [PATCH v6 00/11] implement packed virtqueues Tiwei Bie
2018-09-21 14:06 ` Jens Freimann [this message]
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=20180921140644.oiwl7gwekreflc7v@jenstp.localdomain \
--to=jfreimann@redhat.com \
--cc=Gavin.Hu@arm.com \
--cc=dev@dpdk.org \
--cc=maxime.coquelin@redhat.com \
--cc=tiwei.bie@intel.com \
--cc=zhihong.wang@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).