I checked the kernels. There were major changes in 1995 (before version 2.0), 1998 (before version 2.4), and then again with the introduction of the "O(1) scheduler" (not sure). Here's the code -- unchanged since 2.4 -- that does semctl(GETALL):
Code:
sma = sem_lock(semid);
/* check condition omitted */
nsems = sma->sem_nsems;
err=-EIDRM;
if (sem_checkid(sma,semid)) goto out_unlock;
err = -EACCES;
if (ipcperms (&sma->sem_perm, (cmd==SETVAL||cmd==SETALL)?S_IWUGO:S_IRUGO))
goto out_unlock;
case GETALL: {
ushort __user *array = arg.array;
int i;
if(nsems > SEMMSL_FAST) {
/* omitted code -- relevant only when nsems > 256 */
}
for (i = 0; i < sma->sem_nsems; i++)
sem_io[i] = sma->sem_base[i].semval;
sem_unlock(sma);
err = 0;
if(copy_to_user(array, sem_io, nsems*sizeof(ushort)))
err = -EFAULT;
goto out_free;
Here's the code from 2.0:
Code:
case GETALL:
if (ipcperms (ipcp, S_IRUGO)) return -EACCES;
switch (cmd) {
/* ommitted irrelevant code */
case GETALL:
array = arg.array;
i = verify_area (VERIFY_WRITE, array, nsems*sizeof(ushort));
if (i)
return i;
}
break;
/* skipping case statements */
if (semary[id] == IPC_UNUSED || semary[id] == IPC_NOID)
return -EIDRM;
/* the next line provides the sem_checkid() call from 2.4/2.6 code */
if (sma->sem_perm.seq != (unsigned int) semid / SEMMNI)
return -EIDRM;
switch (cmd) {
case GETALL:
if (ipcperms (ipcp, S_IRUGO))
return -EACCES;
for (i = 0; i < sma->sem_nsems; i++)
sem_io[i] = sma->sem_base[i].semval;
memcpy_tofs (array, sem_io, nsems*sizeof(ushort));
break;
When you break it down, the only difference is in the semlock() call, which is needed on multi-CPU systems. It could be SCO is also similarly limited. Why don't you try a linux 2.0 distribution, like RedHat 5.2, which uses Linux 2.0.36 (and uses the same sem code as above). Install it and benchmark the same code. That would be a great help to all of us, I think.
