Re: [PATCH 2/2] xen: sched: we never get into context_switch() with prev==next

From: Julien Grall <julien.grall@arm.com>
To: Dario Faggioli <dfaggioli@suse.com>,
	Andrii Anisov <andrii.anisov@gmail.com>,
	xen-devel@lists.xenproject.org
Cc: "Juergen Gross" <jgross@suse.com>,
	"Stefano Stabellini" <sstabellini@kernel.org>,
	"Wei Liu" <wei.liu2@citrix.com>,
	"Andrew Cooper" <andrew.cooper3@citrix.com>,
	"George Dunlap" <george.dunlap@citrix.com>,
	"Jan Beulich" <jbeulich@suse.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [PATCH 2/2] xen: sched: we never get into context_switch() with prev==next
Date: Fri, 26 Apr 2019 17:22:03 +0100	[thread overview]
Message-ID: <b0ab9ed7-135b-6240-a0e8-8200e478b6f8@arm.com> (raw)
In-Reply-To: <f136a702e983d174613238619acb2f64bf914fdc.camel@suse.com>

Hi Dario,

On 26/04/2019 16:13, Dario Faggioli wrote:
> On Tue, 2019-04-23 at 12:13 +0300, Andrii Anisov wrote:
>> Hello Dario,
>>
>> On 20.04.19 18:24, Dario Faggioli wrote:
>>> In schedule(), if we pick, as the next vcpu to run (next) the same
>>> one
>>> that is running already (prev), we never get to call
>>> context_switch().
>>
>> And what about `if ( prev != current )` in
>> arm/domain.c:schedule_tail() ?
>>
> You're suggesting that's redundant too, aren't you?
> 
>  From a quick look, it seems to me as well that it would be. I'm ok
> taking care of it, not sure if in this patch, or in another one.

I thought Andrew already queued this patch?

Anyway, I think you are right. We can drop the check in schedule_tail() as well.

Cheers,

-- 
Julien Grall

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