问题
I am using Debian, is there a way to change the niceness of all running process based on their current niceness? For instance change all currently running processes that have a niceness of -20 or -19 to -10. Renice can change a process, and processes for certain users. But as far as I can tell it can't do it based on current niceness.
I am trying to run a program with -20 niceness to try and get around some timing spikes that seem to occur semi-regularly. These might be caused by certain processes with the same priority taking resources. I was hoping to check this with some niceness fiddling.
回答1:
Something to start with in C:
#include <stdio.h>
#include <sys/types.h>
#include <dirent.h>
#include <stdlib.h>
#include <string.h>
static char *prstatname(char *buf, char **endptr)
{
/* parse process name */
char *ptr = buf;
while (*ptr && *ptr != '(') ++ptr;
++ptr;
if (!ptr) return 0;
char *name = ptr;
while (*ptr)
{
if (*ptr == ')' && *(ptr+1) && *(ptr+2) && *(ptr+3)
&& *(ptr+1) == ' ' && *(ptr+3) == ' ')
{
*ptr = 0;
*endptr = ptr + 1;
return name;
}
++ptr;
}
return 0;
}
int main(void)
{
DIR *proc = opendir("/proc");
if (!proc) return 1;
struct dirent *ent;
while ((ent = readdir(proc)))
{
/* check whether filename is all numeric, then it's a process id */
char *endptr;
int pid = strtol(ent->d_name, &endptr, 10);
if (*endptr) continue;
/* combine to '/proc/{pid}/stat' to get information about process */
char statname[64] = {0,};
strcat(statname, "/proc/");
strncat(statname, ent->d_name, 52);
strcat(statname, "/stat");
FILE *pstat = fopen(statname, "r");
if (!pstat) continue;
/* try to read process info */
char buf[1024];
if (!fgets(buf, 1024, pstat))
{
fclose(pstat);
continue;
}
fclose(pstat);
char *name = prstatname(buf, &endptr);
if (!name) continue;
/* nice value is in the 17th field after process name */
int i;
char *tok = strtok(endptr, " ");
for (i = 0; tok && i < 16; ++i) tok = strtok(0, " ");
if (!tok || i < 16) continue;
int nice = strtol(tok, &endptr, 10);
if (*endptr) continue;
printf("[%d] %s -- nice: %d\n", pid, name, nice);
}
}
If you understand this program, you can easily modify it to do what you wanted.
回答2:
To renice all processes with niceness 19 to 10:
ps -eo nice,pid | sed -e 's/^ \+19//;tx;d;:x' | xargs sudo renice 10
Figuring out why this works, or extending it to work with multiple priorities at once is left as an exercise to the reader.
来源:https://stackoverflow.com/questions/32724946/change-niceness-of-all-processes-by-niceness