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samples: bpf: Add BPF support for cpumap tracepoints

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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>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210821002010.845777-9-memxor@gmail.com
This commit is contained in:
Kumar Kartikeya Dwivedi 2021-08-21 05:49:56 +05:30 committed by Alexei Starovoitov
parent 82c450803a
commit 0cf3c2fc4b
1 changed files with 57 additions and 1 deletions
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58
samples/bpf/xdp_sample.bpf.c
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@ -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;
}