linux-kernel - RE: [Xen-devel] [PATCH resend] xen-netback: switch to threaded irq for control ring

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Message-ID: <5520beb1718b40f599a957418c2100e3@AMSPEX02CL03.citrite.net>
Date:   Thu, 22 Sep 2016 10:41:36 +0000
From:   Paul Durrant <Paul.Durrant@...rix.com>
To:     Juergen Gross <jgross@...e.com>,
        "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Wei Liu <wei.liu2@...rix.com>
Subject: RE: [Xen-devel] [PATCH resend] xen-netback: switch to threaded irq
 for control ring

> -----Original Message-----
> From: Juergen Gross [mailto:jgross@...e.com]
> Sent: 22 September 2016 11:39
> To: Paul Durrant <Paul.Durrant@...rix.com>; xen-devel@...ts.xenproject.org;
> netdev@...r.kernel.org; linux-kernel@...r.kernel.org
> Cc: Wei Liu <wei.liu2@...rix.com>
> Subject: Re: [Xen-devel] [PATCH resend] xen-netback: switch to threaded irq
> for control ring
> 
> On 22/09/16 12:31, Paul Durrant wrote:
> >> -----Original Message-----
> >> From: Juergen Gross [mailto:jgross@...e.com]
> >> Sent: 22 September 2016 11:17
> >> To: Paul Durrant <Paul.Durrant@...rix.com>;
> >> xen-devel@...ts.xenproject.org; netdev@...r.kernel.orga
> >> <netdev@...r.kernel.org>; linux- kernel@...r.kernel.org
> >> Cc: Wei Liu <wei.liu2@...rix.com>
> >> Subject: Re: [Xen-devel] [PATCH resend] xen-netback: switch to
> >> threaded irq for control ring
> >>
> >> On 22/09/16 11:09, Paul Durrant wrote:
> >>>> -----Original Message-----
> >>>> From: Xen-devel [mailto:xen-devel-bounces@...ts.xen.org] On Behalf
> >>>> Of Juergen Gross
> >>>> Sent: 22 September 2016 10:03
> >>>> To: xen-devel@...ts.xenproject.org; netdev@...r.kernel.orga; linux-
> >>>> kernel@...r.kernel.org
> >>>> Cc: Juergen Gross <jgross@...e.com>; Wei Liu <wei.liu2@...rix.com>
> >>>> Subject: [Xen-devel] [PATCH resend] xen-netback: switch to threaded
> >>>> irq for control ring
> >>>>
> >>>> Instead of open coding it use the threaded irq mechanism in xen-
> netback.
> >>>>
> >>>> Signed-off-by: Juergen Gross <jgross@...e.com>
> >>>
> >>> How have you tested this change?
> >>
> >> Only compile-tested and loaded the module. As this feature isn't
> >> being used in linux netfront AFAIK it is not easily testable. OTOH
> >> the code modification is rather limited and I've used the threaded
> >> irq in the Xen scsiback driver myself, so I'm rather confident it will work.
> >>
> >
> > OK. How about doing the rx interrupt/task too so that it can be easily
> tested with a linux netfront?
> 
> I'd like to, but this would require some more work. The rx kthread isn't
> activated by an event only, but by a timer, too. This isn't easy to map to the
> threaded irq framework. If, however, you are confident the timer isn't really
> necessary I'd be happy to provide a patch switching the rx task to the
> threaded irq, too.
> 
> And to be honest: this wouldn't verify that the control ring related patch is
> really working. The mechanism itself _is_ working as it is already in use in
> xen-scsiback in a very similar environment.
> 

Ok. If you have confidence then...

Reviewed-by: Paul Durrant <paul.durrant@...rix.com>

> 
> Juergen