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

[Paul Durrant]

> -Original Message-
> From: Juergen Gross [mailto:jgr...@suse.com]
> Sent: 22 September 2016 11:39
> To: Paul Durrant <paul.durr...@citrix.com>; xen-de...@lists.xenproject.org;
> netdev@vger.kernel.org; linux-ker...@vger.kernel.org
> Cc: Wei Liu <wei.l...@citrix.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:jgr...@suse.com]
> >> Sent: 22 September 2016 11:17
> >> To: Paul Durrant <paul.durr...@citrix.com>;
> >> xen-de...@lists.xenproject.org; net...@vger.kernel.orga
> >> <netdev@vger.kernel.org>; linux- ker...@vger.kernel.org
> >> Cc: Wei Liu <wei.l...@citrix.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-boun...@lists.xen.org] On Behalf
> >>>> Of Juergen Gross
> >>>> Sent: 22 September 2016 10:03
> >>>> To: xen-de...@lists.xenproject.org; net...@vger.kernel.orga; linux-
> >>>> ker...@vger.kernel.org
> >>>> Cc: Juergen Gross <jgr...@suse.com>; Wei Liu <wei.l...@citrix.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 <jgr...@suse.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.durr...@citrix.com>

> 
> Juergen

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

[Paul Durrant]

> -Original Message-
> From: Juergen Gross [mailto:jgr...@suse.com]
> Sent: 22 September 2016 11:17
> To: Paul Durrant <paul.durr...@citrix.com>; xen-de...@lists.xenproject.org;
> net...@vger.kernel.orga <netdev@vger.kernel.org>; linux-
> ker...@vger.kernel.org
> Cc: Wei Liu <wei.l...@citrix.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-boun...@lists.xen.org] On Behalf Of
> >> Juergen Gross
> >> Sent: 22 September 2016 10:03
> >> To: xen-de...@lists.xenproject.org; net...@vger.kernel.orga; linux-
> >> ker...@vger.kernel.org
> >> Cc: Juergen Gross <jgr...@suse.com>; Wei Liu <wei.l...@citrix.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 <jgr...@suse.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?

  Paul

> 
> Juergen

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

[Juergen Gross]

On 22/09/16 12:31, Paul Durrant wrote:
>> -Original Message-
>> From: Juergen Gross [mailto:jgr...@suse.com]
>> Sent: 22 September 2016 11:17
>> To: Paul Durrant <paul.durr...@citrix.com>; xen-de...@lists.xenproject.org;
>> net...@vger.kernel.orga <netdev@vger.kernel.org>; linux-
>> ker...@vger.kernel.org
>> Cc: Wei Liu <wei.l...@citrix.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-boun...@lists.xen.org] On Behalf Of
>>>> Juergen Gross
>>>> Sent: 22 September 2016 10:03
>>>> To: xen-de...@lists.xenproject.org; net...@vger.kernel.orga; linux-
>>>> ker...@vger.kernel.org
>>>> Cc: Juergen Gross <jgr...@suse.com>; Wei Liu <wei.l...@citrix.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 <jgr...@suse.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.


Juergen

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

[Juergen Gross]

On 22/09/16 11:09, Paul Durrant wrote:
>> -Original Message-
>> From: Xen-devel [mailto:xen-devel-boun...@lists.xen.org] On Behalf Of
>> Juergen Gross
>> Sent: 22 September 2016 10:03
>> To: xen-de...@lists.xenproject.org; net...@vger.kernel.orga; linux-
>> ker...@vger.kernel.org
>> Cc: Juergen Gross ; Wei Liu 
>> 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 
> 
> 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.


Juergen