95 lines
2.1 KiB
C
95 lines
2.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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// Copyright (c) 2020 Wenbo Zhang
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#include <vmlinux.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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#include "drsnoop.h"
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const volatile pid_t targ_pid = 0;
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const volatile pid_t targ_tgid = 0;
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const volatile __u64 vm_zone_stat_kaddr = 0;
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struct piddata {
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u64 ts;
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u64 nr_free_pages;
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};
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struct {
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__uint(type, BPF_MAP_TYPE_HASH);
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__uint(max_entries, 8192);
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__type(key, u32);
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__type(value, struct piddata);
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} start SEC(".maps");
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struct {
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__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
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__uint(key_size, sizeof(u32));
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__uint(value_size, sizeof(u32));
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} events SEC(".maps");
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SEC("tp_btf/mm_vmscan_direct_reclaim_begin")
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int BPF_PROG(direct_reclaim_begin)
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{
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u64 *vm_zone_stat_kaddrp = (u64*)vm_zone_stat_kaddr;
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u64 id = bpf_get_current_pid_tgid();
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struct piddata piddata = {};
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u32 tgid = id >> 32;
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u32 pid = id;
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if (targ_tgid && targ_tgid != tgid)
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return 0;
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if (targ_pid && targ_pid != pid)
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return 0;
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piddata.ts = bpf_ktime_get_ns();
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if (vm_zone_stat_kaddrp) {
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bpf_probe_read_kernel(&piddata.nr_free_pages,
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sizeof(*vm_zone_stat_kaddrp),
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&vm_zone_stat_kaddrp[NR_FREE_PAGES]);
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}
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bpf_map_update_elem(&start, &pid, &piddata, 0);
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return 0;
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}
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SEC("tp_btf/mm_vmscan_direct_reclaim_end")
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int BPF_PROG(direct_reclaim_end, unsigned long nr_reclaimed)
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{
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u64 id = bpf_get_current_pid_tgid();
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struct piddata *piddatap;
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struct event event = {};
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u32 tgid = id >> 32;
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u32 pid = id;
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s64 delta_ns;
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if (targ_tgid && targ_tgid != tgid)
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return 0;
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if (targ_pid && targ_pid != pid)
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return 0;
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/* fetch timestamp and calculate delta */
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piddatap = bpf_map_lookup_elem(&start, &pid);
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if (!piddatap)
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return 0; /* missed entry */
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delta_ns = bpf_ktime_get_ns() - piddatap->ts;
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if (delta_ns < 0)
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goto cleanup;
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event.pid = pid;
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event.nr_reclaimed = nr_reclaimed;
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event.delta_ns = delta_ns;
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event.nr_free_pages = piddatap->nr_free_pages;
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bpf_get_current_comm(&event.task, TASK_COMM_LEN);
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/* output */
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bpf_perf_event_output(ctx, &events, BPF_F_CURRENT_CPU,
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&event, sizeof(event));
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cleanup:
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bpf_map_delete_elem(&start, &pid);
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return 0;
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}
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char LICENSE[] SEC("license") = "GPL";
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