On Sat, 20 Jun 2020 00:57:20 +0200
Lorenzo Bianconi <lorenzo@xxxxxxxxxx> wrote:
> @@ -273,16 +336,20 @@ static int cpu_map_kthread_run(void *data)
> prefetchw(page);
> }
>
> - m = kmem_cache_alloc_bulk(skbuff_head_cache, gfp, n, skbs);
> + /* Support running another XDP prog on this CPU */
> + nframes = cpu_map_bpf_prog_run_xdp(rcpu, xdp_frames, n, &stats);
> +
If all frames are dropped my XDP program, then we will call
kmem_cache_alloc_bulk() to allocate zero elements. I found this during
my testing[1], and I think we should squash my proposed change in[1].
> + m = kmem_cache_alloc_bulk(skbuff_head_cache, gfp,
> + nframes, skbs);
> if (unlikely(m == 0)) {
> - for (i = 0; i < n; i++)
> + for (i = 0; i < nframes; i++)
> skbs[i] = NULL; /* effect: xdp_return_frame */
> - drops = n;
> + drops += nframes;
> }
>
> local_bh_disable();
> - for (i = 0; i < n; i++) {
> - struct xdp_frame *xdpf = frames[i];
> + for (i = 0; i < nframes; i++) {
> + struct xdp_frame *xdpf = xdp_frames[i];
> struct sk_buff *skb = skbs[i];
> int ret;
[1] https://github.com/xdp-project/xdp-project/blob/master/areas/cpumap/cpumap04-map-xdp-prog.org#observations
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
