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From: "Xie, Huawei" <huawei.xie@intel.com>
To: Ilya Maximets <i.maximets@samsung.com>, "dev@dpdk.org" <dev@dpdk.org>,
 Yuanhan Liu <yuanhan.liu@linux.intel.com>
CC: Dyasly Sergey <s.dyasly@samsung.com>, Jerin Jacob
 <jerin.jacob@caviumnetworks.com>, Jianbo Liu <jianbo.liu@linaro.org>,
 "Thomas Monjalon" <thomas.monjalon@6wind.com>, Tetsuya Mukawa
 <mukawa@igel.co.jp>
Thread-Topic: [PATCH RFC v3 1/3] vhost: use SMP barriers instead of compiler
 ones.
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Date: Fri, 18 Mar 2016 10:27:09 +0000
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Subject: Re: [dpdk-dev] [PATCH RFC v3 1/3] vhost: use SMP barriers instead
 of compiler ones.
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On 3/18/2016 6:23 PM, Ilya Maximets wrote:=0A=
> On 18.03.2016 13:08, Xie, Huawei wrote:=0A=
>> On 2/24/2016 7:47 PM, Ilya Maximets wrote:=0A=
>>>  		 * Wait until it's our turn to add our buffer=0A=
>>> @@ -979,7 +979,7 @@ rte_vhost_dequeue_burst(struct virtio_net *dev, uin=
t16_t queue_id,=0A=
>>>  		entry_success++;=0A=
>>>  	}=0A=
>>>  =0A=
>>> -	rte_compiler_barrier();=0A=
>>> +	rte_smp_rmb();=0A=
>> smp_rmb()?=0A=
> There is no such function 'smp_rmb' in DPDK.=0A=
> But:=0A=
> .../arch/arm/rte_atomic.h:#define rte_smp_rmb() rte_rmb()=0A=
> .../arch/ppc_64/rte_atomic.h:#define rte_smp_rmb() rte_compiler_barrier()=
=0A=
> .../arch/tile/rte_atomic.h:#define rte_smp_rmb() rte_compiler_barrier()=
=0A=
> .../arch/x86/rte_atomic.h:#define rte_smp_rmb() rte_compiler_barrier()=0A=
=0A=
I mean shoudn't be rte_smp_wmb()?=0A=
=0A=
>=0A=
>>>  	vq->used->idx +=3D entry_success;=0A=
>>>  	vhost_log_used_vring(dev, vq, offsetof(struct vring_used, idx),=0A=
>>>  			sizeof(vq->used->idx));=0A=
>>> -- 2.5.0=0A=
>>=0A=
>>=0A=
=0A=