72 lines
1.6 KiB
C
72 lines
1.6 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 "cpufreq.h"
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#include "maps.bpf.h"
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__u32 freqs_mhz[MAX_CPU_NR] = {};
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static struct hist zero;
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struct hist syswide = {};
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struct {
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__uint(type, BPF_MAP_TYPE_HASH);
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__uint(max_entries, MAX_ENTRIES);
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__type(key, struct hkey);
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__type(value, struct hist);
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} hists SEC(".maps");
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#define clamp_umax(VAR, UMAX) \
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asm volatile ( \
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"if %0 <= %[max] goto +1\n" \
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"%0 = %[max]\n" \
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: "+r"(VAR) \
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: [max]"i"(UMAX) \
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)
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SEC("tp_btf/cpu_frequency")
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int BPF_PROG(cpu_frequency, unsigned int state, unsigned int cpu_id)
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{
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if (cpu_id >= MAX_CPU_NR)
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return 0;
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clamp_umax(cpu_id, MAX_CPU_NR - 1);
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freqs_mhz[cpu_id] = state / 1000;
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return 0;
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}
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SEC("perf_event")
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int do_sample(struct bpf_perf_event_data *ctx)
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{
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u32 freq_mhz, pid = bpf_get_current_pid_tgid();
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u64 slot, cpu = bpf_get_smp_processor_id();
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struct hist *hist;
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struct hkey hkey;
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if (cpu >= MAX_CPU_NR)
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return 0;
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clamp_umax(cpu, MAX_CPU_NR - 1);
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freq_mhz = freqs_mhz[cpu];
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if (!freq_mhz)
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return 0;
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/*
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* The range of the linear histogram is 0 ~ 5000mhz,
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* and the step size is 200.
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*/
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slot = freq_mhz / HIST_STEP_SIZE;
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if (slot >= MAX_SLOTS)
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slot = MAX_SLOTS - 1;
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__sync_fetch_and_add(&syswide.slots[slot], 1);
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if (!pid)
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return 0;
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bpf_get_current_comm(&hkey.comm, sizeof(hkey.comm));
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hist = bpf_map_lookup_or_try_init(&hists, &hkey, &zero);
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if (!hist)
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return 0;
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__sync_fetch_and_add(&hist->slots[slot], 1);
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return 0;
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}
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char LICENSE[] SEC("license") = "GPL";
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