Re: [snabb-devel] Re: memory barriers in virtq.lua?

From: Luke Gorrie <luke-vEt0keKvJLw@public.gmane.org>
To: "snabb-devel-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org"
	<snabb-devel-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org>
Cc: "dev-VfR2kkLFssw@public.gmane.org"
	<dev-VfR2kkLFssw@public.gmane.org>,
	VirtualOpenSystems Technical Team
	<tech-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org>,
	virtualization-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
Subject: Re: [snabb-devel] Re: memory barriers in virtq.lua?
Date: Wed, 8 Apr 2015 05:40:11 +0200	[thread overview]
Message-ID: <CAA2XHbehi0rFuEGXDA=KTeVr5My1gvUOpOjFP5oSEUiYozrdCA@mail.gmail.com> (raw)
In-Reply-To: <20150407172849-mutt-send-email-mst-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

On 7 April 2015 at 17:30, Michael S. Tsirkin <mst-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:

> Just guessing from the available info:
>
> I think you refer to this:
>         The driver MUST handle spurious interrupts from the device.
>
> The intent is to be able to handle some spurious interrupts once in a
> while.  AFAIK linux triggers the message if it gets a huge number of
> spurious interrupts for an extended period of time.
> For example, this will trigger if the device does not clear interrupt
> line after interrupt register read.
>

Thanks for that info.

The only spurious interrupt that I think we need is one when vhost-user
reconnects. That would be to cover the case where the vswitch is restarted
after writing used->idx but before sending the interrupt.

Or perhaps there is a better solution to that case?

Looking forward to getting an upstream vhost-user reconnect. one thing at a
time.. :)

Cheers,
-Luke