netdev - Re: [patch net-next] virtio_net: add support for Byte Queue Limits

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Message-ID: <ZkcMthuRwhMsWJgn@nanopsycho.orion>
Date: Fri, 17 May 2024 09:52:22 +0200
From: Jiri Pirko <jiri@...nulli.us>
To: "Michael S. Tsirkin" <mst@...hat.com>
Cc: Jason Wang <jasowang@...hat.com>, netdev@...r.kernel.org,
	davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
	pabeni@...hat.com, xuanzhuo@...ux.alibaba.com,
	virtualization@...ts.linux.dev, ast@...nel.org,
	daniel@...earbox.net, hawk@...nel.org, john.fastabend@...il.com
Subject: Re: [patch net-next] virtio_net: add support for Byte Queue Limits

Thu, May 16, 2024 at 09:04:41PM CEST, mst@...hat.com wrote:
>On Thu, May 16, 2024 at 05:25:20PM +0200, Jiri Pirko wrote:
>> 
>> >I'd expect a regression if any to be in a streaming benchmark.
>> 
>> Can you elaborate?
>
>BQL does two things that can hurt throughput:
>- limits amount of data in the queue - can limit bandwidth
>  if we now get queue underruns
>- adds CPU overhead - can limit bandwidth if CPU bound
>
>So checking result of a streaming benchmark seems important.

I understand. Didn't see any degradation in TCP_STREAM netperf. But I
will try to extend the testing.

Thanks!

>
>
>-- 
>MST
>