Hi all,
In many application we use select() system call for delay.
example:
select(0,NULL,NULL,NULL,&t1);
select() for delay is very inefficient. I modified sys_select() code for
efficiency .Here are the changes to fs/select.c.
Please suggest on these changes.
I know nanosleep() can be used instead of select(), but please suggest
on my changes.
file : fs/select.c
function : sys_select()
timeout += sec * (unsigned long) HZ;
}
}
-
+
+
ret = -EINVAL;
if (n < 0)
goto out_nofds;
-
+ if ( (n == 0) && (inp == NULL) && (outp == NULL) &&
(exp== NULL)){
+ printf("\n I am inside new select condition timeout
%d\n",timeout);
+ set_current_state(TASK_INTERRUPTIBLE);
+ ret = 0;
+ timeout = schedule_timeout(timeout);
+ if (signal_pending(current))
+ ret = -ERESTARTNOHAND;
+ if (tvp && !(current->personality & STICKY_TIMEOUTS)) {
+ time_t sec = 0, usec = 0;
+ if (timeout) {
+ sec = timeout / HZ;
+ usec = timeout % HZ;
+ usec *= (1000000/HZ);
+ }
+ put_user(sec, &tvp->tv_sec);
+ put_user(usec, &tvp->tv_usec);
+ }
+ current->state = TASK_RUNNING;
+ goto out_nofds;
+ }
+
/* max_fdset can increase, so grab it once to avoid race */
max_fdset = current->files->max_fdset;
if (n > max_fdset)
Thank you very much.
Thanks for your assistances.
Madhu K.S.
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