sync_count.py

sync_count.py

from __future__ import print_function
from sys import flags, maxsize
from bcc import BPF, PerfHWConfig

b= BPF (text="""
//create a map with default

BPF_HASH(last);
//BPF_HASH(map);

int do_trace(struct pt_regs *ctx){
    u64 ts,*tsp,delta,key=0;
    u64 count,*index=0;
    u64 key1=1;
    //find key from map,return a pointer
    index=last.lookup(&key1);
    tsp= last.lookup(&key);
    if(tsp!=NULL)
    {
        //Returns the time as nanoseconds.
        delta=bpf_ktime_get_ns()- *tsp;
        // output if time is less than 1 second
        if(delta<1000000000){
            bpf_trace_printk("%d\\n",count,delta/1000000);
        }
        last.delete(&key);
    }
    //add a counter to trace
    if(index==0)
    {
        count=1;
    }
    else{
        count=++*index;
        last.delete(&key1);
    }
    last.update(&key1,&count);
    
    ts=bpf_ktime_get_ns();
    last.update(&key,&ts);
    return 0;
}
""")

b.attach_kprobe(event=b.get_syscall_fnname("sync"),fn_name="do_trace")
print("tracing for sync")

start=0
# while 1:
#     (task,pid,cpu,flags,ts,ms)=b.trace_fields()
#     if start==0:
#         start=ts
#     ts=ts-start
#     print("At time %.2f s: multiple syncs detected, last %s ms ago " % (ts, ms))
while 1:
    try:
        (task,pid,cpu,flags,ts,msg)=b.trace_fields()
        [count,ms]=msg.split(",")
        if start==0:
            start=ts
        ts=ts-start
        print("At time %.2f s: %smultiple syncs detected, last %s ms ago " % (ts,count,ms))
    except KeyboardInterrupt:
        exit()