From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: "Xia, Chenbo" <chenbo.xia@intel.com>,
"Liu, Changpeng" <changpeng.liu@intel.com>,
"dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [PATCH] vhost: use try_lock in rte_vhost_vring_call
Date: Tue, 20 Sep 2022 09:23:58 +0200 [thread overview]
Message-ID: <af4c2381-6e9a-5218-68e9-7356d407620c@redhat.com> (raw)
In-Reply-To: <SN6PR11MB3504DEF441C81F2B16A913829C4C9@SN6PR11MB3504.namprd11.prod.outlook.com>
On 9/20/22 04:53, Xia, Chenbo wrote:
>> -----Original Message-----
>> From: Liu, Changpeng <changpeng.liu@intel.com>
>> Sent: Tuesday, September 20, 2022 10:34 AM
>> To: Xia, Chenbo <chenbo.xia@intel.com>; dev@dpdk.org
>> Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
>> Subject: RE: [PATCH] vhost: use try_lock in rte_vhost_vring_call
>>
>> Hi Bo,
>>
>>> -----Original Message-----
>>> From: Xia, Chenbo <chenbo.xia@intel.com>
>>> Sent: Tuesday, September 20, 2022 10:25 AM
>>> To: Liu, Changpeng <changpeng.liu@intel.com>; dev@dpdk.org
>>> Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
>>> Subject: RE: [PATCH] vhost: use try_lock in rte_vhost_vring_call
>>>
>>> Hi Changpeng,
>>>
>>>> -----Original Message-----
>>>> From: Liu, Changpeng <changpeng.liu@intel.com>
>>>> Sent: Tuesday, September 6, 2022 10:22 AM
>>>> To: dev@dpdk.org
>>>> Cc: Liu, Changpeng <changpeng.liu@intel.com>; Maxime Coquelin
>>>> <maxime.coquelin@redhat.com>; Xia, Chenbo <chenbo.xia@intel.com>
>>>> Subject: [PATCH] vhost: use try_lock in rte_vhost_vring_call
>>>>
>>>> Note that this function is in data path, so the thread context
>>>> may not same as socket messages processing context, by using
>>>> try_lock here, users can have another try in case of VQ's access
>>>> lock is held by `vhost-events` thread.
>>>
>>> Better to describe the issue this patch wants to fix and how does
>>> it fix.
>>>
>>> I remember it's a bz issue, do you want to backport? And it has
>>> some bz ID, we need to add it in commit message.
>> Actually it's my intention not to add bz ID, as I think for this bz ID,
>> It's better not to lock all VQ's access lock for KICK/CALLFD messages,
>
> Do you plan to add this change? I think that may be an improvement to current
> locking implementation.
>
> Maxime, what do you think of this idea about only locking specific queue when
> handling vring related message (not global config like mem table)?
I think this is not a good idea.
For example SET_VRING_KICK can currently call
translate_ring_addresses(), which itself can call numa_realloc().
numa_realloc() may reallocate the dev, so you don't want it to be used
by other queues while it happens.
>> What do you think? If this is identified as a fix, I can backport it to
>> 22.05.
>
> You can decide, if this is planned to be the fix, just backport. I am just
> thinking if this is not the fix for the bz, do we still need this?
>
> Thanks,
> Chenbo
>
>>>
>>>>
>>>> Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
>>>> ---
>>>> lib/vhost/vhost.c | 6 +++++-
>>>> 1 file changed, 5 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c
>>>> index 60cb05a0ff..072d2acb7b 100644
>>>> --- a/lib/vhost/vhost.c
>>>> +++ b/lib/vhost/vhost.c
>>>> @@ -1329,7 +1329,11 @@ rte_vhost_vring_call(int vid, uint16_t
>> vring_idx)
>>>> if (!vq)
>>>> return -1;
>>>>
>>>> - rte_spinlock_lock(&vq->access_lock);
>>>> + if (!rte_spinlock_trylock(&vq->access_lock)) {
>>>> + VHOST_LOG_CONFIG(dev->ifname, DEBUG,
>>>
>>> Should use VHOST_LOG_DATA
>> OK.
>>>
>>> Thanks,
>>> Chenbo
>>>
>>>> + "failed to kick guest, virtqueue busy.\n");
>>>> + return -1;
>>>> + }
>>>>
>>>> if (vq_is_packed(dev))
>>>> vhost_vring_call_packed(dev, vq);
>>>> --
>>>> 2.21.3
>
next prev parent reply other threads:[~2022-09-20 7:24 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-06 2:22 Changpeng Liu
2022-09-06 21:15 ` Stephen Hemminger
2022-09-07 0:40 ` Liu, Changpeng
2022-09-20 7:12 ` Maxime Coquelin
2022-09-20 2:24 ` Xia, Chenbo
2022-09-20 2:34 ` Liu, Changpeng
2022-09-20 2:53 ` Xia, Chenbo
2022-09-20 3:00 ` Liu, Changpeng
2022-09-20 7:23 ` Maxime Coquelin [this message]
2022-09-20 7:30 ` Maxime Coquelin
2022-09-20 7:19 ` Maxime Coquelin
2022-09-20 7:29 ` Liu, Changpeng
2022-09-20 7:34 ` Maxime Coquelin
2022-09-20 7:45 ` Liu, Changpeng
2022-09-20 8:12 ` Maxime Coquelin
2022-09-20 8:43 ` Liu, Changpeng
2022-09-21 9:41 ` Maxime Coquelin
2022-09-21 9:52 ` Liu, Changpeng
2022-10-11 11:56 ` Maxime Coquelin
2022-10-12 6:40 ` [PATCH v2] vhost: add new `rte_vhost_vring_call_nonblock` API Changpeng Liu
2022-10-13 7:56 ` Maxime Coquelin
2022-10-17 6:46 ` Xia, Chenbo
2022-10-17 7:17 ` Liu, Changpeng
2022-10-17 7:14 ` [PATCH v3] " Changpeng Liu
2022-10-17 7:39 ` Xia, Chenbo
2022-10-17 7:50 ` Liu, Changpeng
2022-10-17 7:48 ` [PATCH v4] " Changpeng Liu
2022-10-19 5:27 ` Xia, Chenbo
2022-10-26 9:24 ` Xia, Chenbo
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