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From: "Van Haaren, Harry" <harry.van.haaren@intel.com>
To: 宋捷 <songj@zctt.com>, 'users' <users@dpdk.org>,
	'Stephen Hemminger' <stephen@networkplumber.org>
Subject: Re: [dpdk-users] ojectes from the mempool are disorderd by rte_mempool_generic_get
Date: Tue, 24 Mar 2020 10:54:30 +0000
Message-ID: <BYAPR11MB3143A238424806D7E1785160D7F10@BYAPR11MB3143.namprd11.prod.outlook.com> (raw)
In-Reply-To: <000001d6019b$519bec20$f4d3c460$@zctt.com>

Hi Jie,

Mempools don't provide any promise of dequeuing objects in a specific order. The mempool data-structure actually has a per-lcore cache which allows recycling buffers on a per-lcore basis, providing better performance (and certainly breaking your ordering hopes).

If you need strict I/O ordering from a datastructure, I suggest using a rte_ring. The ring datastructure is a FIFO, so the first packets you enqueue will be the first to dequeue too. Regardless of the rte_ring_dequeue_burst() size parameter, calling 1x 10 times, or 10x calls with 1 packet, the mbufs returned will be in the same order.

Hope that helps, -Harry

From: ^[$BAW>9^[(B <songj@zctt.com>
Sent: Tuesday, March 24, 2020 5:16 AM
To: 'users' <users@dpdk.org>; 'Stephen Hemminger' <stephen@networkplumber.org>; Van Haaren, Harry <harry.van.haaren@intel.com>
Subject: ojectes from the mempool are disorderd by rte_mempool_generic_get

Hi all,

I created a packet mbuf pool (rte_pktmbuf_pool_create) for saving some packets, And using rte_mempool_obj_iter for put hundreds of packets (from a pcap file) into the packet pool.

Finally I need to get ten packets from the packet pool.
If I call rte_mempool_generic_get for one packet each time, and try 10 times, then I can get ten packets in correct order;
But if call rte_mempool_generic_get for ten packets one time, then these ten packets are disordered.

So using rte_mempool_generic_get for getting multi objects, it will return disorder objects from the mbuf pool?
If there^[$B!G^[(Bs any other way for can get objects from the mempool orderly

I used DPDK18.05



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Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-24  5:16 宋捷
2020-03-24 10:54 ` Van Haaren, Harry [this message]

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