On 12/07/2016 05:33 PM, Federico Reghenzani wrote: > > > 2016-12-07 17:21 GMT+01:00 Vlastimil Babka <vbabka@xxxxxxx > <mailto:vbabka@xxxxxxx>>: > > On 12/07/2016 04:39 PM, Federico Reghenzani wrote: > > Hello, > > > > I'm working on Real-Time applications in Linux. `mlockall()` is a > > typical syscall used in RT processes in order to avoid page faults. > > However, the use of this syscall is strongly limited by ulimits, so > > basically all RT processes that want to call `mlockall()` have to be > > executed with root privileges. > > Is it not possible to change the ulimits with e.g. prlimit? > > > Yes, but it requires a synchronization between non-root process and root > process. > Because the root process has to change the limits before the non-root > process executes the mlockall(). Would it work if you did that between fork() and exec()? If you can spawn them like this, that is. > Just to provide an example, another syscall used in RT tasks is the > sched_setscheduler() that also suffers > the limitation of ulimits, but it accepts the pid so the scheduling > policy can be enforced by a root process to > any other process. > > > > > What I would like to have is a syscall that accept a "pid", so a process > > spawned by root would be able to enforce the memory locking to other > > non-root processes. The prototypes would be: > > > > int mlockall(int flags, pid_t pid); > > int munlockall(pid_t pid); > > > > I checked the source code and it seems to me quite easy to add this > > syscall variant. > > > > I'm writing here to have a feedback before starting to edit the code. Do > > you think that this is a good approach? > > > > > > Thank you, > > Federico > > > > -- > > *Federico Reghenzani* > > PhD Candidate > > Politecnico di Milano > > Dipartimento di Elettronica, Informazione e Bioingegneria > > > > > > > -- > *Federico Reghenzani* > PhD Candidate > Politecnico di Milano > Dipartimento di Elettronica, Informazione e Bioingegneria > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>