From: "Xie, Huawei" <huawei.xie@intel.com>
To: Yuanhan Liu <yuanhan.liu@linux.intel.com>,
Steffen Bauch <mail@steffenbauch.de>,
Nikita Kalyazin <n.kalyazin@samsung.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v5 resend 07/12] virtio: resolve for control queue
Date: Mon, 12 Oct 2015 09:56:39 +0000 [thread overview]
Message-ID: <C37D651A908B024F974696C65296B57B4B118E32@SHSMSX101.ccr.corp.intel.com> (raw)
In-Reply-To: <C37D651A908B024F974696C65296B57B4B118D66@SHSMSX101.ccr.corp.intel.com>
On 10/12/2015 10:33 AM, Xie, Huawei wrote:
> On 10/12/2015 9:39 AM, Yuanhan Liu wrote:
>> On Thu, Oct 08, 2015 at 10:51:02PM +0200, Steffen Bauch wrote:
>>> On 10/08/2015 05:32 PM, Nikita Kalyazin wrote:
>>>> Hi Yuanhan,
>>>>
>>>>
>>>> As I understand, the dead loop happened here (virtio_send_command):
>>>> while (vq->vq_used_cons_idx == vq->vq_ring.used->idx) {
> Nikita:
>
> Didn't review the whole patch, but happen to find a serious problem in
> the code snippet here, as volatile isn't used, compiler will assume the
> memory will not be changed outside and do only one comparison.
>
> Try add volatile prefix, and it might fix your problem.
Read other mails in this thread, if the specific queue is due to wrong
queue index.
Fix the volatile in the code, otherwise if first time no match, the code
will go to dead loop directly and no chance to compare again in
optimized code.
>>>> rte_rmb();
>>>> usleep(100);
>>>> }
>>>>
>>>> Could you explain why wrong config reading caused that and how correct reading helps to avoid?
>> Wrong config reading results to wrong config->max_virtqueue_pairs, which
>> ends up with wrong ctrl vq index being set:
>>
>> PMD: virtio_send_command(): vq->vq_queue_index = 37120
>>
>> Note that you need enable CONFIG_RTE_LIBRTE_VIRTIO_DEBUG_INIT to see above
>> debug log.
>>
>> That is to say we are waiting for the backend to consume a non-exist
>> queue, and that's how the dead loop comes.
>>
>>
>>> Hi,
>>>
>>> I just recognized that this dead loop is the same one that I have
>>> experienced (see
>>> http://dpdk.org/ml/archives/dev/2015-October/024737.html for
>>> reference). Just applying the changes in this patch (only 07/12)
>>> will not fix the dead loop at least in my setup.
>> Try to enable CONFIG_RTE_LIBRTE_VIRTIO_DEBUG_INIT, and dump more log?
>>
>> --yliu
>>
>
next prev parent reply other threads:[~2015-10-12 9:56 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-18 15:10 [dpdk-dev] [PATCH v5 resend 00/12] vhost-user multiple queues enabling Yuanhan Liu
2015-09-18 15:10 ` [dpdk-dev] [PATCH v5 resend 01/12] vhost-user: add protocol features support Yuanhan Liu
2015-09-18 15:10 ` [dpdk-dev] [PATCH v5 resend 02/12] vhost-user: add VHOST_USER_GET_QUEUE_NUM message Yuanhan Liu
2015-09-18 15:10 ` [dpdk-dev] [PATCH v5 resend 03/12] vhost: vring queue setup for multiple queue support Yuanhan Liu
2015-09-20 13:58 ` Marcel Apfelbaum
2015-09-21 2:06 ` Yuanhan Liu
2015-09-21 17:56 ` Marcel Apfelbaum
2015-09-22 7:31 ` Yuanhan Liu
2015-09-22 8:10 ` Marcel Apfelbaum
2015-09-22 8:34 ` Yuanhan Liu
2015-09-22 8:47 ` Marcel Apfelbaum
2015-09-22 9:21 ` Yuanhan Liu
2015-09-22 10:06 ` Marcel Apfelbaum
2015-09-22 14:22 ` Yuanhan Liu
2015-09-22 14:51 ` Marcel Apfelbaum
2015-09-23 3:46 ` Yuanhan Liu
2015-09-24 9:51 ` Marcel Apfelbaum
2015-09-21 9:07 ` Michael S. Tsirkin
2015-09-18 15:10 ` [dpdk-dev] [PATCH v5 resend 04/12] vhost: rxtx: prepare work " Yuanhan Liu
2015-09-20 9:29 ` Michael S. Tsirkin
2015-09-21 2:25 ` Yuanhan Liu
2015-09-21 9:04 ` Michael S. Tsirkin
2015-09-22 2:54 ` Yuanhan Liu
2015-09-18 15:10 ` [dpdk-dev] [PATCH v5 resend 05/12] vhost: add VHOST_USER_SET_VRING_ENABLE message Yuanhan Liu
2015-09-20 9:37 ` Michael S. Tsirkin
2015-09-21 2:22 ` Yuanhan Liu
2015-09-21 9:02 ` Michael S. Tsirkin
2015-09-22 2:21 ` Yuanhan Liu
2015-09-23 8:43 ` Yuanhan Liu
2015-09-18 15:10 ` [dpdk-dev] [PATCH v5 resend 06/12] vhost-user: handle VHOST_USER_RESET_OWNER correctly Yuanhan Liu
2015-09-18 15:10 ` [dpdk-dev] [PATCH v5 resend 07/12] virtio: resolve for control queue Yuanhan Liu
2015-09-20 9:21 ` Michael S. Tsirkin
2015-09-21 6:36 ` Yuanhan Liu
2015-10-08 15:32 ` Nikita Kalyazin
2015-10-08 20:51 ` Steffen Bauch
2015-10-09 7:11 ` Nikita Kalyazin
2015-10-12 8:39 ` Yuanhan Liu
2015-10-12 9:31 ` Xie, Huawei
2015-10-12 9:56 ` Xie, Huawei [this message]
2015-10-12 20:58 ` Steffen Bauch
2015-10-13 9:54 ` Yuanhan Liu
2015-09-18 15:10 ` [dpdk-dev] [PATCH v5 resend 08/12] vhost-user: enable vhost-user multiple queue Yuanhan Liu
2015-09-18 15:10 ` [dpdk-dev] [PATCH v5 resend 09/12] vhost: add API bind a virtq to a specific core Yuanhan Liu
2015-09-18 15:10 ` [dpdk-dev] [PATCH v5 resend 10/12] ixgbe: support VMDq RSS in non-SRIOV environment Yuanhan Liu
2015-09-18 15:11 ` [dpdk-dev] [PATCH v5 resend 11/12] examples/vhost: demonstrate the usage of vhost mq feature Yuanhan Liu
2015-09-18 15:11 ` [dpdk-dev] [PATCH v5 resend 12/12] examples/vhost: add per queue stats Yuanhan Liu
2015-09-20 11:48 ` [dpdk-dev] [PATCH v5 resend 00/12] vhost-user multiple queues enabling Marcel Apfelbaum
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