[PATCH bpf-next v4 08/22] samples: bpf: Add BPF support for cpumap tracepoints
From: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Date: 2021-08-21 00:20:47
Also in:
bpf
Subsystem:
bpf [general] (safe dynamic programs and tools), the rest, xdp (express data path) · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds, David S. Miller, Jakub Kicinski, Jesper Dangaard Brouer, John Fastabend
These are invoked in two places, when the XDP frame or SKB (for generic XDP) enqueued to the ptr_ring (cpumap_enqueue) and when kthread processes the frame after invoking the CPUMAP program for it (returning stats for the batch). We use cpumap_map_id to filter on the map_id as a way to avoid printing incorrect stats for parallel sessions of xdp_redirect_cpu. Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> --- samples/bpf/xdp_sample.bpf.c | 58 +++++++++++++++++++++++++++++++++++- 1 file changed, 57 insertions(+), 1 deletion(-)
diff --git a/samples/bpf/xdp_sample.bpf.c b/samples/bpf/xdp_sample.bpf.c
index 53ab5a972405..f01a5529751c 100644
--- a/samples/bpf/xdp_sample.bpf.c
+++ b/samples/bpf/xdp_sample.bpf.c@@ -8,6 +8,8 @@ array_map rx_cnt SEC(".maps"); array_map redir_err_cnt SEC(".maps"); +array_map cpumap_enqueue_cnt SEC(".maps"); +array_map cpumap_kthread_cnt SEC(".maps"); array_map exception_cnt SEC(".maps"); const volatile int nr_cpus = 0;
@@ -19,6 +21,8 @@ const volatile int nr_cpus = 0; const volatile int from_match[32] = {}; const volatile int to_match[32] = {}; +int cpumap_map_id = 0; + /* Find if b is part of set a, but if a is empty set then evaluate to true */ #define IN_SET(a, b) \ ({ \
@@ -112,6 +116,59 @@ int BPF_PROG(tp_xdp_redirect_map, const struct net_device *dev, return xdp_redirect_collect_stat(dev->ifindex, err); } +SEC("tp_btf/xdp_cpumap_enqueue") +int BPF_PROG(tp_xdp_cpumap_enqueue, int map_id, unsigned int processed, + unsigned int drops, int to_cpu) +{ + u32 cpu = bpf_get_smp_processor_id(); + struct datarec *rec; + u32 idx; + + if (cpumap_map_id && cpumap_map_id != map_id) + return 0; + + idx = to_cpu * nr_cpus + cpu; + rec = bpf_map_lookup_elem(&cpumap_enqueue_cnt, &idx); + if (!rec) + return 0; + NO_TEAR_ADD(rec->processed, processed); + NO_TEAR_ADD(rec->dropped, drops); + /* Record bulk events, then userspace can calc average bulk size */ + if (processed > 0) + NO_TEAR_INC(rec->issue); + /* Inception: It's possible to detect overload situations, via + * this tracepoint. This can be used for creating a feedback + * loop to XDP, which can take appropriate actions to mitigate + * this overload situation. + */ + return 0; +} + +SEC("tp_btf/xdp_cpumap_kthread") +int BPF_PROG(tp_xdp_cpumap_kthread, int map_id, unsigned int processed, + unsigned int drops, int sched, struct xdp_cpumap_stats *xdp_stats) +{ + struct datarec *rec; + u32 cpu; + + if (cpumap_map_id && cpumap_map_id != map_id) + return 0; + + cpu = bpf_get_smp_processor_id(); + rec = bpf_map_lookup_elem(&cpumap_kthread_cnt, &cpu); + if (!rec) + return 0; + NO_TEAR_ADD(rec->processed, processed); + NO_TEAR_ADD(rec->dropped, drops); + NO_TEAR_ADD(rec->xdp_pass, xdp_stats->pass); + NO_TEAR_ADD(rec->xdp_drop, xdp_stats->drop); + NO_TEAR_ADD(rec->xdp_redirect, xdp_stats->redirect); + /* Count times kthread yielded CPU via schedule call */ + if (sched) + NO_TEAR_INC(rec->issue); + return 0; +} + SEC("tp_btf/xdp_exception") int BPF_PROG(tp_xdp_exception, const struct net_device *dev, const struct bpf_prog *xdp, u32 act)
@@ -136,4 +193,3 @@ int BPF_PROG(tp_xdp_exception, const struct net_device *dev, return 0; } -
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2.33.0