From: Zoltan Kiss <zoltan.kiss@citrix•com>
To: David Vrabel <david.vrabel@citrix•com>, Wei Liu <wei.liu2@citrix•com>
Cc: <netdev@vger•kernel.org>, <xen-devel@lists•xen.org>,
Ian Campbell <ian.campbell@citrix•com>
Subject: Re: [Xen-devel] [PATCH net v2 2/3] xen-netback: don't stop dealloc kthread too early
Date: Mon, 11 Aug 2014 15:13:41 +0100 [thread overview]
Message-ID: <53E8CF95.5050209@citrix.com> (raw)
In-Reply-To: <53E8CBF5.1030600@citrix.com>
On 11/08/14 14:58, David Vrabel wrote:
> On 11/08/14 14:48, Wei Liu wrote:
>> On Mon, Aug 11, 2014 at 01:10:12PM +0100, David Vrabel wrote:
>>> On 08/08/14 17:37, Wei Liu wrote:
>> [...]
>>>> if (tx_evtchn == rx_evtchn) {
>>>> /* feature-split-event-channels == 0 */
>>>> @@ -687,6 +700,9 @@ void xenvif_disconnect(struct xenvif *vif)
>>>> queue->task = NULL;
>>>> }
>>>>
>>>> + wait_event(queue->inflight_wq,
>>>> + atomic_read(&queue->inflight_packets) == 0);
>>>
>>> Just make the dealloc task not stop unless it has deallocated all
>>> outstanding requests. There's no need for another wait queue here.
>>>
>>
>> Are you suggesting something like
>>
>> while (atomic_read(&queue->inflight_packets) !=0)
>> schedule_timeout(SOME_TIMEOUT);
>
> No. That would be awful!
>
> Add the test to the kthread itself:
>
> int xenvif_dealloc_kthread(void *data)
> {
> struct xenvif_queue *queue = data;
>
> while (atomic_read(&queue->inflight_packets) > 0
> || !kthread_should_stop()) {
> [...]
>
> etc.
>
> Although, the main loop is a bit confused, so I suggest adding:
>
> static bool xenvif_dealloc_thread_should_stop(struct xenvif_queue *q)
> {
> /* Dealloc thread must remain running if there are any inflight
> * packets so it can properly dealloc them when they complete.
> */
> return atomic_read(&queue->inflight_packets) == 0
> && kthread_should_stop();
> }
>
> And cleaning it up a bit (the while() could be a for(;;)).
I would recommend this:
---
@@ -2066,7 +2066,7 @@ int xenvif_dealloc_kthread(void *data)
wait_event_interruptible(queue->dealloc_wq,
tx_dealloc_work_todo(queue) ||
kthread_should_stop());
- if (kthread_should_stop())
+ if (kthread_should_stop() && !atomic_read(&queue->inflight_packets))
break;
xenvif_tx_dealloc_action(queue);
---
If kthread_stop called, this will keep the main loop running until all callbacks are called.
Then it proceeds to the exit branch, otherwise doesn't disrupt normal operation.
next prev parent reply other threads:[~2014-08-11 14:13 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-08 16:37 [PATCH net v2 0/3] xen-netback: synchronisation between core driver and netback Wei Liu
2014-08-08 16:37 ` [PATCH net v2 1/3] xen-netback: move NAPI add/remove calls Wei Liu
2014-08-08 16:49 ` Sergei Shtylyov
2014-08-08 16:52 ` Wei Liu
2014-08-11 12:35 ` [Xen-devel] " David Vrabel
2014-08-11 12:49 ` Zoltan Kiss
2014-08-11 13:01 ` David Vrabel
2014-08-11 13:14 ` Zoltan Kiss
2014-08-11 13:43 ` Wei Liu
2014-08-11 13:59 ` David Vrabel
2014-08-11 14:08 ` Wei Liu
2014-08-08 16:37 ` [PATCH net v2 2/3] xen-netback: don't stop dealloc kthread too early Wei Liu
2014-08-11 12:10 ` [Xen-devel] " David Vrabel
2014-08-11 13:48 ` Wei Liu
2014-08-11 13:58 ` David Vrabel
2014-08-11 14:13 ` Zoltan Kiss [this message]
2014-08-11 14:44 ` Wei Liu
2014-08-11 15:23 ` David Vrabel
2014-08-11 20:39 ` Wei Liu
2014-08-11 14:31 ` Wei Liu
2014-08-11 14:34 ` David Vrabel
2014-08-11 14:39 ` Wei Liu
2014-08-08 16:37 ` [PATCH net v2 3/3] xen-netback: remove loop waiting function Wei Liu
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