From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [74.208.4.200]) by dpdk.org (Postfix) with ESMTP id 463D468CD for ; Wed, 19 Feb 2014 15:03:12 +0100 (CET) Received: from mailout-us.gmx.com ([172.19.198.47]) by mrigmx.server.lan (mrigmxus001) with ESMTP (Nemesis) id 0MWC9l-1WnP7V30pt-00XI4i for ; Wed, 19 Feb 2014 15:04:36 +0100 Received: (qmail 23821 invoked by uid 0); 19 Feb 2014 14:04:36 -0000 Received: from 188.219.172.131 by rms-us022 with HTTP Date: Wed, 19 Feb 2014 09:04:33 -0500 From: "Mario Gianni" Message-ID: <20140219140433.259460@gmx.com> MIME-Version: 1.0 To: "Benson, Bryan" ,"Periklis Akritidis" X-Flags: 0001 X-Mailer: GMX.com Web Mailer x-registered: 0 X-GMX-UID: ptx2cz4E3zOl2w14bXghMe5+IGRvb4B0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit X-Content-Filtered-By: Mailman/MimeDel 2.1.15 Cc: dev@dpdk.org Subject: Re: [dpdk-dev] problem with rte_pktmbuf_prepend (possible bug?) X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 19 Feb 2014 14:03:12 -0000 This is my init function: pktmbuf_pool[socketid] = rte_mempool_create( name, APP_DEFAULT_MEMPOOL_BUFFERS, APP_DEFAULT_MBUF_SIZE, APP_DEFAULT_MEMPOOL_CACHE_SIZE, sizeof(struct rte_pktmbuf_pool_private), rte_pktmbuf_pool_init, NULL, rte_pktmbuf_init, NULL, socketid, 0); I copied it from a sample code. Anyway it seems to me that mbuf_free does not reset the *data pointer, actually I have partially resolved by prepending manually the data without moving the * data pointer at all albeit it's not a very clean solution. Could this be a bug in the DPDK mbuf_free() function? ----- Original Message ----- From: Benson, Bryan Sent: 02/18/14 06:16 PM To: Periklis Akritidis, Mario Gianni Subject: RE: [dpdk-dev] problem with rte_pktmbuf_prepend (possible bug?) Whoa, be careful, we used a custom init function and had a nasty bug because we assumed it was called on mbuf_free as well. The rte_pktmbuf_init function pointer passed into mempool create is only used at pool initialization time, not when an mbuf is freed - A reference to the obj_initi function is not stored anywhere for future use during mbuf_free. Some of the fields are reset when the NIC has completed the send of the mbufs, but it does not use a custom function ptr. Thanks, Bryan Benson ________________________________________ From: dev [dev-bounces@dpdk.org] on behalf of Periklis Akritidis [akritid@niometrics.com] Sent: Tuesday, February 18, 2014 6:19 AM To: Mario Gianni Cc: dev@dpdk.org Subject: Re: [dpdk-dev] problem with rte_pktmbuf_prepend (possible bug?) Hi Mario, Are you passing rte_pktmbuf_init as the obj_init argument to rte_mempool_create? It is called when the mbuf if freed and it will reset the fields. I vaguely remember I had the same issue at some point and resolved it somehow. This comes to mind. Cheers, Periklis On 18 Feb, 2014, at 6:27 pm, Mario Gianni wrote: > Hi all, I'm experimenting some code with DPDK v1.5.0 and I have the following problem: > > I have a thread that receives packets from NIC, once I received a packet I want to prepend some data to it and I try to do so through the function rte_pktmbuf_prepend() > then the packet is enqueued in a ring buffer where it will be used by a client thread before being dropped through the function rte_pktmbuf_free() called by the client thread. > > Now, if I try to send packets to this program I have the following behaviour: > In a first time it seems to work correctly, then after a certain number of received packets (approximately the same number as the number of mbufs present in the mempool) if I call the rte_pktmbuf_headroom it returns that the headroom is shrinking more than the expected, until after a certain number of packets the headroom goes to zero. > > It seems like that when I call the rte_pktmbuf_free() function it doesn't reset the data position inside the mbuf, so when I call for a second time the mbuf the headroom continues to shrink until it finishes. > > > Do you have any idea of this strange behaviour?Could it be a bug in the prepend/free function? > > > Thank you, > > Mario