Does the rte_eth_tx_burst() function is multi-threaded safe when sending pkt in same port and same queue ?

Does the rte_eth_tx_burst() function is multi-threaded safe when sending pkt in same port and same queue ?

[chen_lp]

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Re: Does the rte_eth_tx_burst() function is multi-threaded safe when sending pkt in same port and same queue ?

[Stephen Hemminger]

The rx and tx functions are safe only if a queue is not shared by
multiple threads (or the threads synchronize through some other
mechanism). The safest design is to only use a queue on a single core.
You will see different architectures in the examples. Some use one
queue per core, and others use separate receive and transmit cores.

On Wed, Jan 8, 2014 at 8:16 PM, chen_lp <chen_lp-YYSg24PYQUdBDgjK7y7TUQ@public.gmane.org> wrote:
>
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Re: Does the rte_eth_tx_burst() function is multi-threaded safe when sending pkt in same port and same queue ?

[金健]

But when I read the code of  l2fwd (v1.5.1 examples), I found that two cores share only one queue of a port.

And it doesn't use any lock or other mechanism to ensure the safety.

How is it OK?

----- Original Message ----- 
From: "Stephen Hemminger" <stephen@networkplumber.org>
To: "chen_lp" <chen_lp@neusoft.com>
Cc: <dev@dpdk.org>
Sent: Thursday, January 09, 2014 2:28 PM
Subject: Re: [dpdk-dev] Does the rte_eth_tx_burst() function is multi-threaded safe when sending pkt in same port and same queue ?


> The rx and tx functions are safe only if a queue is not shared by
> multiple threads (or the threads synchronize through some other
> mechanism). The safest design is to only use a queue on a single core.
> You will see different architectures in the examples. Some use one
> queue per core, and others use separate receive and transmit cores.
> 
> On Wed, Jan 8, 2014 at 8:16 PM, chen_lp <chen_lp@neusoft.com> wrote:
>>
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>> Confidentiality Notice: The information contained in this e-mail and any accompanying attachment(s)
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