systemd (Was Re: tmpfs for strategic directories)

[Gustavo Alves]

I've made some benchmarks starting a dummy service (do not call any programs
or kill) and a samba server on my notebook. I run those tests 4 times and
discarded the first one. Each test execute 100 times the command:

service dummy restart = 0,023ms
service smb restart = 0,158ms
c application = 0,016ms

After I made this change:

--- /etc/init.d/functions    2010-05-26 13:26:00.000000000 -0300
+++ /etc/init.d/functions    2010-05-26 13:03:01.000000000 -0300
@@ -305,12 +305,13 @@
                if checkpid $pid 2>&1; then
                # TERM first, then KILL if not dead
                kill -TERM $pid >/dev/null 2>&1
-               usleep 100000
-               if checkpid $pid && sleep 1 &&
+                           usleep 1000
+               if checkpid $pid && usleep 100000 &&
+                  checkpid $pid && sleep 1 &&
                   checkpid $pid && sleep $delay &&
                   checkpid $pid ; then
                                 kill -KILL $pid >/dev/null 2>&1
-                usleep 100000
+                usleep 50000
                fi
                 fi
             checkpid $pid

After this, the time dropped 60%:

service smb restart = 0,051ms

And finally I wrote this C application:

#include <unistd.h>
#include <stdlib.h>
#include <sys/wait.h>

int main(int argc,char *argv[]) {
  int pid,ret,a;

  for(a=0;a<100;a++) {
    if((pid=fork())==0) {
      execlp("smbd","smbd","-D",NULL);
      exit(-1);
    }
    waitpid(pid,&ret,0);
    kill(pid,9);
  }
  exit(0);
}

This is the final result:

service dummy restart = 0,023ms
service smb restart = 0,158ms
service smb restart (after hack) = 0,051ms
c application = 0,016ms

We are talking about to gain 0.035ms per process on init using C (service
restart) in my notebook.

----
Gustavo Junior Alves
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