On Fri, Feb 21, 2020 at 9:30 AM Eelco Chaudron <echaudro@xxxxxxxxxx> wrote: > > > > On 20 Feb 2020, at 23:49, William Tu wrote: > > > Hi, > > > > I'm trying to save some CPU cycles when there is no packet arrives. > > I enable the poll syscall option of xdpsock, by doing > > > > $ ./xdpsock -r -p -S -i ens16 > > sock0@ens160:0 rxdrop xdp-skb poll() > > pps pkts 1.00 > > rx 0 0 > > tx 0 0 > > > > Since there is no packet coming, I though by calling poll() > > system call, the xdpsock process will be blocked and CPU utilization > > should be way under 100%. However, I'm still seeing 100% > > CPU utilization. Am I understanding this correctly? > > Hi William, I can remember I saw this in the past two with this code. It > had something to do with the way xdpsock waits for the buffers to be > free’ ed by the kernel. What I can remember it had something to do > with the veth interfaces also. > > I do remember that I fixed it in the tutorial for AF_XDP: > https://github.com/xdp-project/xdp-tutorial/blob/master/advanced03-AF_XDP/af_xdp_user.c Eelco, Do you remember exactly what you had to fix in the xdpsock sample? Your tutorial is quite a rewrite so it is hard for me to tell exactly which of all the changes that fix this problem. The reason I ask is that it would be nice to fix this in the sample too. Thanks: Magnus > Maybe you can see if you have the same problem with this example. > > //Eelco > > > > Thanks, > > William >
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