On 11/01/2017 04:44 AM, Jesper Dangaard Brouer wrote: > Discovered that the compiler laid-out asm code in suboptimal way > when studying perf report during benchmarking of cpumap. Help > the compiler by the marking unlikely code paths. > > Signed-off-by: Jesper Dangaard Brouer <bro...@redhat.com> > --- > kernel/bpf/cpumap.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c > index 86e29cbf7827..ce5b669003b2 100644 > --- a/kernel/bpf/cpumap.c > +++ b/kernel/bpf/cpumap.c > @@ -208,7 +208,7 @@ static struct xdp_pkt *convert_to_xdp_pkt(struct xdp_buff > *xdp) > headroom = xdp->data - xdp->data_hard_start; > metasize = xdp->data - xdp->data_meta; > metasize = metasize > 0 ? metasize : 0; > - if ((headroom - metasize) < sizeof(*xdp_pkt)) > + if (unlikely((headroom - metasize) < sizeof(*xdp_pkt))) > return NULL; > > /* Store info in top of packet */ > @@ -656,7 +656,7 @@ int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, > struct xdp_buff *xdp, > struct xdp_pkt *xdp_pkt; > > xdp_pkt = convert_to_xdp_pkt(xdp); > - if (!xdp_pkt) > + if (unlikely(!xdp_pkt)) > return -EOVERFLOW; > > /* Info needed when constructing SKB on remote CPU */ >
Seems OK to me, just curious is this noticeable at pps benchmarks? Acked-by: John Fastabend <john.fastab...@gmail.com>
