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 09:30:21 +0200 [thread overview]
Message-ID: <7c3269f3-8c7e-d0b1-59d3-65ca297c898d@redhat.com> (raw)
In-Reply-To: <af4c2381-6e9a-5218-68e9-7356d407620c@redhat.com>
On 9/20/22 09:23, Maxime Coquelin wrote:
>
>
> 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.
Hmm, actually that may be possible because numa_realloc() reallocs the
dev only if it is not running.
So maybe you can propose something, but you will have to test it
carefully with use-cases involving NUMA reallocation.
>>> 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 7:30 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
2022-09-20 7:30 ` Maxime Coquelin [this message]
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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