282 lines
7.0 KiB
C
282 lines
7.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/version.h>
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#include <linux/ptrace.h>
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#include <uapi/linux/bpf.h>
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#include <bpf/bpf_helpers.h>
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/*
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* The CPU number, cstate number and pstate number are based
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* on 96boards Hikey with octa CA53 CPUs.
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*
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* Every CPU have three idle states for cstate:
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* WFI, CPU_OFF, CLUSTER_OFF
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*
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* Every CPU have 5 operating points:
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* 208MHz, 432MHz, 729MHz, 960MHz, 1200MHz
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*
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* This code is based on these assumption and other platforms
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* need to adjust these definitions.
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*/
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#define MAX_CPU 8
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#define MAX_PSTATE_ENTRIES 5
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#define MAX_CSTATE_ENTRIES 3
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static int cpu_opps[] = { 208000, 432000, 729000, 960000, 1200000 };
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/*
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* my_map structure is used to record cstate and pstate index and
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* timestamp (Idx, Ts), when new event incoming we need to update
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* combination for new state index and timestamp (Idx`, Ts`).
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*
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* Based on (Idx, Ts) and (Idx`, Ts`) we can calculate the time
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* interval for the previous state: Duration(Idx) = Ts` - Ts.
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*
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* Every CPU has one below array for recording state index and
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* timestamp, and record for cstate and pstate saperately:
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*
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* +--------------------------+
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* | cstate timestamp |
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* +--------------------------+
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* | cstate index |
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* +--------------------------+
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* | pstate timestamp |
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* +--------------------------+
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* | pstate index |
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* +--------------------------+
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*/
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#define MAP_OFF_CSTATE_TIME 0
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#define MAP_OFF_CSTATE_IDX 1
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#define MAP_OFF_PSTATE_TIME 2
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#define MAP_OFF_PSTATE_IDX 3
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#define MAP_OFF_NUM 4
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struct {
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__uint(type, BPF_MAP_TYPE_ARRAY);
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__type(key, u32);
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__type(value, u64);
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__uint(max_entries, MAX_CPU * MAP_OFF_NUM);
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} my_map SEC(".maps");
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/* cstate_duration records duration time for every idle state per CPU */
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struct {
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__uint(type, BPF_MAP_TYPE_ARRAY);
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__type(key, u32);
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__type(value, u64);
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__uint(max_entries, MAX_CPU * MAX_CSTATE_ENTRIES);
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} cstate_duration SEC(".maps");
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/* pstate_duration records duration time for every operating point per CPU */
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struct {
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__uint(type, BPF_MAP_TYPE_ARRAY);
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__type(key, u32);
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__type(value, u64);
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__uint(max_entries, MAX_CPU * MAX_PSTATE_ENTRIES);
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} pstate_duration SEC(".maps");
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/*
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* The trace events for cpu_idle and cpu_frequency are taken from:
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* /sys/kernel/tracing/events/power/cpu_idle/format
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* /sys/kernel/tracing/events/power/cpu_frequency/format
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*
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* These two events have same format, so define one common structure.
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*/
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struct cpu_args {
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u64 pad;
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u32 state;
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u32 cpu_id;
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};
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/* calculate pstate index, returns MAX_PSTATE_ENTRIES for failure */
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static u32 find_cpu_pstate_idx(u32 frequency)
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{
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u32 i;
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for (i = 0; i < sizeof(cpu_opps) / sizeof(u32); i++) {
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if (frequency == cpu_opps[i])
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return i;
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}
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return i;
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}
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SEC("tracepoint/power/cpu_idle")
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int bpf_prog1(struct cpu_args *ctx)
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{
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u64 *cts, *pts, *cstate, *pstate, prev_state, cur_ts, delta;
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u32 key, cpu, pstate_idx;
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u64 *val;
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if (ctx->cpu_id > MAX_CPU)
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return 0;
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cpu = ctx->cpu_id;
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key = cpu * MAP_OFF_NUM + MAP_OFF_CSTATE_TIME;
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cts = bpf_map_lookup_elem(&my_map, &key);
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if (!cts)
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return 0;
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key = cpu * MAP_OFF_NUM + MAP_OFF_CSTATE_IDX;
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cstate = bpf_map_lookup_elem(&my_map, &key);
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if (!cstate)
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return 0;
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key = cpu * MAP_OFF_NUM + MAP_OFF_PSTATE_TIME;
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pts = bpf_map_lookup_elem(&my_map, &key);
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if (!pts)
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return 0;
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key = cpu * MAP_OFF_NUM + MAP_OFF_PSTATE_IDX;
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pstate = bpf_map_lookup_elem(&my_map, &key);
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if (!pstate)
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return 0;
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prev_state = *cstate;
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*cstate = ctx->state;
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if (!*cts) {
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*cts = bpf_ktime_get_ns();
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return 0;
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}
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cur_ts = bpf_ktime_get_ns();
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delta = cur_ts - *cts;
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*cts = cur_ts;
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/*
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* When state doesn't equal to (u32)-1, the cpu will enter
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* one idle state; for this case we need to record interval
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* for the pstate.
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*
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* OPP2
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* +---------------------+
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* OPP1 | |
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* ---------+ |
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* | Idle state
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* +---------------
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*
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* |<- pstate duration ->|
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* ^ ^
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* pts cur_ts
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*/
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if (ctx->state != (u32)-1) {
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/* record pstate after have first cpu_frequency event */
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if (!*pts)
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return 0;
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delta = cur_ts - *pts;
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pstate_idx = find_cpu_pstate_idx(*pstate);
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if (pstate_idx >= MAX_PSTATE_ENTRIES)
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return 0;
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key = cpu * MAX_PSTATE_ENTRIES + pstate_idx;
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val = bpf_map_lookup_elem(&pstate_duration, &key);
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if (val)
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__sync_fetch_and_add((long *)val, delta);
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/*
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* When state equal to (u32)-1, the cpu just exits from one
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* specific idle state; for this case we need to record
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* interval for the pstate.
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*
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* OPP2
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* -----------+
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* | OPP1
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* | +-----------
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* | Idle state |
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* +---------------------+
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*
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* |<- cstate duration ->|
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* ^ ^
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* cts cur_ts
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*/
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} else {
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key = cpu * MAX_CSTATE_ENTRIES + prev_state;
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val = bpf_map_lookup_elem(&cstate_duration, &key);
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if (val)
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__sync_fetch_and_add((long *)val, delta);
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}
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/* Update timestamp for pstate as new start time */
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if (*pts)
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*pts = cur_ts;
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return 0;
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}
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SEC("tracepoint/power/cpu_frequency")
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int bpf_prog2(struct cpu_args *ctx)
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{
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u64 *pts, *cstate, *pstate, prev_state, cur_ts, delta;
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u32 key, cpu, pstate_idx;
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u64 *val;
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cpu = ctx->cpu_id;
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key = cpu * MAP_OFF_NUM + MAP_OFF_PSTATE_TIME;
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pts = bpf_map_lookup_elem(&my_map, &key);
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if (!pts)
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return 0;
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key = cpu * MAP_OFF_NUM + MAP_OFF_PSTATE_IDX;
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pstate = bpf_map_lookup_elem(&my_map, &key);
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if (!pstate)
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return 0;
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key = cpu * MAP_OFF_NUM + MAP_OFF_CSTATE_IDX;
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cstate = bpf_map_lookup_elem(&my_map, &key);
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if (!cstate)
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return 0;
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prev_state = *pstate;
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*pstate = ctx->state;
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if (!*pts) {
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*pts = bpf_ktime_get_ns();
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return 0;
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}
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cur_ts = bpf_ktime_get_ns();
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delta = cur_ts - *pts;
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*pts = cur_ts;
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/* When CPU is in idle, bail out to skip pstate statistics */
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if (*cstate != (u32)(-1))
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return 0;
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/*
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* The cpu changes to another different OPP (in below diagram
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* change frequency from OPP3 to OPP1), need recording interval
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* for previous frequency OPP3 and update timestamp as start
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* time for new frequency OPP1.
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*
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* OPP3
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* +---------------------+
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* OPP2 | |
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* ---------+ |
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* | OPP1
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* +---------------
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*
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* |<- pstate duration ->|
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* ^ ^
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* pts cur_ts
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*/
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pstate_idx = find_cpu_pstate_idx(*pstate);
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if (pstate_idx >= MAX_PSTATE_ENTRIES)
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return 0;
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key = cpu * MAX_PSTATE_ENTRIES + pstate_idx;
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val = bpf_map_lookup_elem(&pstate_duration, &key);
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if (val)
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__sync_fetch_and_add((long *)val, delta);
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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u32 _version SEC("version") = LINUX_VERSION_CODE;
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