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Add mlockall and SCHED_FIFO support

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The attached patch adds support for mlockall() as well as the SCHED_FIFO
real-time scheduler. It should result in reduced (and more consistent)
latency. Usage is documented in all the documents.
This commit is contained in:
John Hasler
2009-02-10 17:59:57 +01:00
committed by Miroslav Lichvar
parent cdc22df903
commit 35e662d810
11 changed files with 258 additions and 2 deletions
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63
sys_linux.c
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@@ -39,6 +39,17 @@
#include <assert.h>
#include <sys/utsname.h>
#if defined(HAVE_SCHED_SETSCHEDULER)
# include <sched.h>
int SchedPriority = 0;
#endif
#if defined(HAVE_MLOCKALL)
# include <sys/mman.h>
#include <sys/resource.h>
int LockAll = 0;
#endif
#ifdef FEAT_LINUXCAPS
#include <sys/types.h>
#include <pwd.h>
@@ -898,6 +909,58 @@ SYS_Linux_DropRoot(char *user)
/* ================================================== */
#if defined(HAVE_SCHED_SETSCHEDULER)
/* Install SCHED_FIFO real-time scheduler with specified priority */
void SYS_Linux_SetScheduler(int SchedPriority)
{
int pmax, pmin;
struct sched_param sched;
if (SchedPriority > 0) {
sched.sched_priority = SchedPriority;
pmax = sched_get_priority_max(SCHED_FIFO);
pmin = sched_get_priority_min(SCHED_FIFO);
if ( SchedPriority > pmax ) {
sched.sched_priority = pmax;
}
else if ( SchedPriority < pmin ) {
sched.sched_priority = pmin;
}
if ( sched_setscheduler(0, SCHED_FIFO, &sched) == -1 ) {
LOG(LOGS_ERR, LOGF_SysLinux, "sched_setscheduler() failed");
}
else {
LOG(LOGS_INFO, LOGF_SysLinux, "Enabled SCHED_FIFO with priority %d", sched.sched_priority);
}
}
}
#endif /* HAVE_SCHED_SETSCHEDULER */
#if defined(HAVE_MLOCKALL)
/* Lock the process into RAM so that it will never be swapped out */
void SYS_Linux_MemLockAll(int LockAll)
{
struct rlimit rlim;
if (LockAll == 1 ) {
/* Make sure that we will be able to lock all the memory we need */
/* even after dropping privileges. This does not actually reaerve any memory */
rlim.rlim_max = RLIM_INFINITY;
rlim.rlim_cur = RLIM_INFINITY;
if (setrlimit(RLIMIT_MEMLOCK, &rlim) < 0) {
LOG(LOGS_ERR, LOGF_SysLinux, "setrlimit() failed: not locking into RAM");
}
else {
if (mlockall(MCL_CURRENT|MCL_FUTURE) < 0) {
LOG(LOGS_ERR, LOGF_SysLinux, "mlockall() failed");
}
else {
LOG(LOGS_INFO, LOGF_SysLinux, "Successfully locked into RAM");
}
}
}
}
#endif /* HAVE_MLOCKALL */
#endif /* LINUX */
/* vim:ts=8