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From: Thomas Monjalon <thomas.monjalon@6wind.com>
To: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Cc: dev@dpdk.org, Ilya Maximets <i.maximets@samsung.com>,
	Huawei Xie <huawei.xie@intel.com>,
	bruce.richardson@intel.com, Dyasly Sergey <s.dyasly@samsung.com>,
	Jerin Jacob <jerin.jacob@caviumnetworks.com>,
	Jianbo Liu <jianbo.liu@linaro.org>,
	Tetsuya Mukawa <mukawa@igel.co.jp>
Subject: Re: [dpdk-dev] [PATCH RFC v3 0/3] Thread safe rte_vhost_enqueue_burst().
Date: Fri, 18 Mar 2016 10:34:56 +0100	[thread overview]
Message-ID: <3519170.fnd0yd7nVF@xps13> (raw)
In-Reply-To: <20160318091614.GT979@yliu-dev.sh.intel.com>

2016-03-18 17:16, Yuanhan Liu:
> On Fri, Mar 18, 2016 at 09:09:04AM +0100, Thomas Monjalon wrote:
> > 2016-03-18 16:00, Yuanhan Liu:
> > > On Thu, Mar 17, 2016 at 04:29:32PM +0100, Thomas Monjalon wrote:
> > > > 2016-02-24 14:47, Ilya Maximets:
> > > > > Implementation of rte_vhost_enqueue_burst() based on lockless ring-buffer
> > > > > algorithm and contains almost all to be thread-safe, but it's not.
> > > > > 
> > > > > This set adds required changes.
> > > > > 
> > > > > First patch in set is a standalone patch that fixes many times discussed
> > > > > issue with barriers on different architectures.
> > > > > 
> > > > > Second and third adds fixes to make rte_vhost_enqueue_burst thread safe.
> > > > 
> > > > My understanding is that we do not want to pollute Rx/Tx with locks.
> > > > 
> > > > Huawei, Yuanhan, Bruce, do you confirm?
> > > 
> > > Huawei would like to do that, and I'm behind that. Let's do it.
> > 
> > I'm not sure to understand. What do you want to do exactly?
> 
> I was thinking we are on the same page :(

Yes we are on the same page.
But it's better to make things explicit.

There should be no lock in Rx/Tx drivers (including vhost).
The locking must be done by the caller (application level).
That's why this series "Thread safe rte_vhost_enqueue_burst" is rejected.

> "do not want to pollute Rx/Tx with locks" == "remove lockless Rx/Tx, the
> proposal from Huawei", right?
> 
> In another way, I'm behind the following patch from Huawei:
> 
>     http://dpdk.org/dev/patchwork/patch/9740/

The patch "vhost: remove lockless enqueue to the virtio ring" must me
reworked in 2 patches:
1/ announce API change
2/ remove locks

Please avoid talking about removing "lockless" when actually removing locks.

Thanks

  reply	other threads:[~2016-03-18  9:36 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-24 11:47 Ilya Maximets
2016-02-24 11:47 ` [dpdk-dev] [PATCH RFC v3 1/3] vhost: use SMP barriers instead of compiler ones Ilya Maximets
2016-03-18 10:08   ` Xie, Huawei
2016-03-18 10:23     ` Ilya Maximets
2016-03-18 10:27       ` Xie, Huawei
2016-03-18 10:39         ` Ilya Maximets
2016-03-18 10:47           ` Xie, Huawei
2016-03-18 11:00             ` Ilya Maximets
     [not found]               ` <C37D651A908B024F974696C65296B57B4C67825C@SHSMSX101.ccr.corp.intel.com>
     [not found]                 ` <56EBE9AE.9070400@samsung.com>
     [not found]                   ` <56EBF256.8040409@samsung.com>
2016-03-18 12:28                     ` Ilya Maximets
2016-03-18 12:23   ` [dpdk-dev] [PATCH v4] " Ilya Maximets
2016-03-18 12:41     ` Yuanhan Liu
2016-03-21  4:49       ` Ilya Maximets
2016-03-21 14:07         ` Ananyev, Konstantin
2016-03-21 17:25           ` Xie, Huawei
2016-03-21 17:36             ` Ananyev, Konstantin
2016-03-23 14:07     ` Xie, Huawei
2016-03-31 13:46       ` Thomas Monjalon
2016-02-24 11:47 ` [dpdk-dev] [PATCH RFC v3 2/3] vhost: make buf vector for scatter RX local Ilya Maximets
2016-02-24 11:47 ` [dpdk-dev] [PATCH RFC v3 3/3] vhost: avoid reordering of used->idx and last_used_idx updating Ilya Maximets
2016-03-17 15:29 ` [dpdk-dev] [PATCH RFC v3 0/3] Thread safe rte_vhost_enqueue_burst() Thomas Monjalon
2016-03-18  8:00   ` Yuanhan Liu
2016-03-18  8:09     ` Thomas Monjalon
2016-03-18  9:16       ` Yuanhan Liu
2016-03-18  9:34         ` Thomas Monjalon [this message]
2016-03-18  9:46           ` Yuanhan Liu
2016-03-18  9:55             ` Ilya Maximets
2016-03-18 10:10               ` Xie, Huawei
2016-03-18 10:24                 ` Thomas Monjalon

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