Dear Stephen,
Yes, you are right. Thanks very much for your help, very appreciated. It is much more clear to me now. extern struct lcore_conf lcore_conf[RTE_MAX_LCORE]; Best wishes, Xiaoban ________________________________ From: Stephen Hemminger <step...@networkplumber.org> Sent: Monday, November 27, 2017 11:06:13 PM To: Wu, Xiaoban Cc: us...@dpdk.org; dev@dpdk.org Subject: Re: [dpdk-dev] A question about the possible race condition in the l3fwd example? On Tue, 28 Nov 2017 02:22:57 +0000 "Wu, Xiaoban" <xiaoban...@student.uml.edu> wrote: > Dear All, > > > I am studying the source code of the l3fwd example. I am confused about a > possible race condition in the l3fwd_lpm_simple_forward(). > > > In this function it calls send_single_packet(), which executes the following > code, > > len = qconf->tx_mbufs[port].len; > qconf->tx_mbufs[port].m_table[len] = m; > len++; > > As you can see, if two threads are trying to call send_single_packet() at the > same time and send different packets to the same port, which writes the > value to the same array and updates the same counter 'len', then the race > condition happens, so we might lose packets. > > Can anybody please clarify if this indeed brings race condition? If yes, then > why we want to design it in this way, just for high performance? If no, why? > > Thanks very much for your help. > > Best wishes, > Xiaoban > > > qconf is in in a per core data structure, so it is impossible for sharing to happen.
