如何在后台运行脚本并控制数量？

Question

I have some test programs, their names are

bingo_64k.llc_pref
bingo.llc_pref
bingo_multitable_pc+addr_addr.llc_pref
bingo_multitable_pc+addr_addr_pc+offs.llc_pref
bingo_multitable_pc+addr_addr_pc+offs_pc.llc_pref

I want to use these programs to run some benchmarks. I wrote a script to control the parameters. The name of the script is run.sh . I only need ./run.sh --benchmark=benchmark_name_index --binary=Executable_file to run. The run.sh script will automatically add other parameters at runtime.

Eg ./run.sh --benchmark=1 --binary=bingo_64k.llc_pref

Each benchmark takes about three hours to run. I want them to execute in parallel. I plan to put each run in the background to run. I wrote the following script file. The name is tem.sh . Note that I wrote the name of all the test program in the evaluate_prefetch file.

BENCHMARK_NUM=5
while read LINE
do
    for ((i=1; i<=$BENCHMARK_NUM; i++))
    do
    
        # sleep 2
        # array=($(pidof $LINE))
        # echo ${#array[@]}
        # while [ ${#array[@]} -ge 10 ]
        # do
        #   sleep 60
        #   array=($(pidof $LINE))
        # done

        cmd="./run.sh --benchmark=$i --binary=$LINE &"
        $cmd
    done
done < evaluate_prefetch

1. After I run the above script. I found that I can see these processes through top command. But when I use jobs , nothing is displayed.

2. I don't want to run too many in the background at once, it may affect other people. I want to run only 10 at a time. What should I do? I use the following code to determine how many are currently running. But the following function is very slow to execute, and did not get the correct result.

      get_process_num(){
            process_num=0
            while read LINE
            do
                sleep 2
                array=($(pidof $LINE))
                let process_num=$process_num+${#array[@]}
                echo $process_num
            done < evaluate_prefetch
        }

3. ./tem.sh & Should I run the above script like this so that when I exit the terminal, it will still run in the background?

4. I always accidentally make some errors when I run it. How can I kill these processes all at once and then rerun them? I tried killall sleep . But when I execute top , I can still see many sleep processes.

Answer 1

There are a total of 140 priorities and two distinct priority ranges implemented in Linux. The first one is a nice value (niceness) which ranges from -20 (highest priority value) to 19 (lowest priority value) and the default is 0. The other is the real-time priority, which ranges from 1 to 99 by default, then 100 to 139 are meant for user-space.

From the top outputs, you'll notice that there is a column called PR and PRI which show the priority of a process.

NI – is the nice value, which is a user-space concept, while PR or PRI – is the process's actual priority, as seen by the Linux kernel.

Total number of priorities = 140 Real time priority range(PR or PRI): 0 to 99 User space priority range: 100 to 139

Nice value range (NI): -20 to 19

PR = 20 + NI

PR = 20 + (-20 to + 19)

PR = 20 + -20 to 20 + 19

PR = 0 to 39 which is same as 100 to 139.

But if you see a rt rather than a number as shown in the screenshot below, it basically means the process is running under real-time scheduling priority.

to change the niceness:

$ nice -n niceness-value [command args]

OR

$ nice -niceness-value [command args] 

OR

$ nice --adjustment=niceness-value [command args]