From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jiri Pirko <jiri@resnulli.us>
Cc: netdev@vger.kernel.org, davem@davemloft.net, edumazet@google.com,
kuba@kernel.org, pabeni@redhat.com, jasowang@redhat.com,
xuanzhuo@linux.alibaba.com, virtualization@lists.linux.dev,
ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org,
john.fastabend@gmail.com
Subject: Re: [patch net-next] virtio_net: add support for Byte Queue Limits
Date: Wed, 15 May 2024 04:20:04 -0400 [thread overview]
Message-ID: <20240515041909-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <ZkRlcBU0Nb3O-Kg1@nanopsycho.orion>
On Wed, May 15, 2024 at 09:34:08AM +0200, Jiri Pirko wrote:
> Fri, May 10, 2024 at 01:27:08PM CEST, mst@redhat.com wrote:
> >On Fri, May 10, 2024 at 01:11:49PM +0200, Jiri Pirko wrote:
> >> Fri, May 10, 2024 at 12:52:52PM CEST, mst@redhat.com wrote:
> >> >On Fri, May 10, 2024 at 12:37:15PM +0200, Jiri Pirko wrote:
> >> >> Thu, May 09, 2024 at 04:28:12PM CEST, mst@redhat.com wrote:
> >> >> >On Thu, May 09, 2024 at 03:31:56PM +0200, Jiri Pirko wrote:
> >> >> >> Thu, May 09, 2024 at 02:41:39PM CEST, mst@redhat.com wrote:
> >> >> >> >On Thu, May 09, 2024 at 01:46:15PM +0200, Jiri Pirko wrote:
> >> >> >> >> From: Jiri Pirko <jiri@nvidia.com>
> >> >> >> >>
> >> >> >> >> Add support for Byte Queue Limits (BQL).
> >> >> >> >>
> >> >> >> >> Signed-off-by: Jiri Pirko <jiri@nvidia.com>
> >> >> >> >
> >> >> >> >Can we get more detail on the benefits you observe etc?
> >> >> >> >Thanks!
> >> >> >>
> >> >> >> More info about the BQL in general is here:
> >> >> >> https://lwn.net/Articles/469652/
> >> >> >
> >> >> >I know about BQL in general. We discussed BQL for virtio in the past
> >> >> >mostly I got the feedback from net core maintainers that it likely won't
> >> >> >benefit virtio.
> >> >>
> >> >> Do you have some link to that, or is it this thread:
> >> >> https://lore.kernel.org/netdev/21384cb5-99a6-7431-1039-b356521e1bc3@redhat.com/
> >> >
> >> >
> >> >A quick search on lore turned up this, for example:
> >> >https://lore.kernel.org/all/a11eee78-b2a1-3dbc-4821-b5f4bfaae819@gmail.com/
> >>
> >> Says:
> >> "Note that NIC with many TX queues make BQL almost useless, only adding extra
> >> overhead."
> >>
> >> But virtio can have one tx queue, I guess that could be quite common
> >> configuration in lot of deployments.
> >
> >Not sure we should worry about performance for these though.
> >What I am saying is this should come with some benchmarking
> >results.
>
> I did some measurements with VDPA, backed by ConnectX6dx NIC, single
> queue pair:
>
> super_netperf 200 -H $ip -l 45 -t TCP_STREAM &
> nice -n 20 netperf -H $ip -l 10 -t TCP_RR
>
> RR result with no bql:
> 29.95
> 32.74
> 28.77
>
> RR result with bql:
> 222.98
> 159.81
> 197.88
>
Okay. And on the other hand, any measureable degradation with
multiqueue and when testing throughput?
>
> >
> >
> >>
> >> >
> >> >
> >> >
> >> >
> >> >> I don't see why virtio should be any different from other
> >> >> drivers/devices that benefit from bql. HOL blocking is the same here are
> >> >> everywhere.
> >> >>
> >> >> >
> >> >> >So I'm asking, what kind of benefit do you observe?
> >> >>
> >> >> I don't have measurements at hand, will attach them to v2.
> >> >>
> >> >> Thanks!
> >> >>
> >> >> >
> >> >> >--
> >> >> >MST
> >> >> >
> >> >
> >
next prev parent reply other threads:[~2024-05-15 8:20 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-09 11:46 [patch net-next] virtio_net: add support for Byte Queue Limits Jiri Pirko
2024-05-09 12:41 ` Michael S. Tsirkin
2024-05-09 13:31 ` Jiri Pirko
2024-05-09 14:28 ` Michael S. Tsirkin
2024-05-10 4:25 ` Jason Wang
2024-05-10 10:37 ` Jiri Pirko
2024-05-10 10:52 ` Michael S. Tsirkin
2024-05-10 11:11 ` Jiri Pirko
2024-05-10 11:27 ` Michael S. Tsirkin
2024-05-10 11:36 ` Jiri Pirko
2024-05-15 7:34 ` Jiri Pirko
2024-05-15 8:20 ` Michael S. Tsirkin [this message]
2024-05-15 10:12 ` Jiri Pirko
2024-05-15 12:54 ` Jiri Pirko
2024-05-16 4:48 ` Jason Wang
2024-05-16 10:54 ` Jiri Pirko
2024-05-16 12:31 ` Michael S. Tsirkin
2024-05-16 15:25 ` Jiri Pirko
2024-05-16 19:04 ` Michael S. Tsirkin
2024-05-17 7:52 ` Jiri Pirko
2024-05-10 4:25 ` Jason Wang
2024-05-10 7:11 ` Heng Qi
2024-05-10 10:35 ` Jiri Pirko
2024-05-20 12:48 ` Jiri Pirko
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