[PATCH 2/3] virprocess: add the SCHED_DEADLINE scheduling policy
Sasha Algisi
sasha.algisi at edu.unito.it
Mon Aug 1 17:11:45 UTC 2022
Tasks associated to virtual CPUs, IO Threads and Emulator processes
can be created with the SCHED_DEADLINE policy. The policy is described
in details here: https://docs.kernel.org/scheduler/sched-deadline.html
It requires the following parameters (all in nanoseconds):
1) runtime
2) deadline
3) period
It must always holds that: runtime <= deadline <= period.
The kernel enforces that the values stay within [1024, 2^63-1].
Note, however, that a smaller range could be set (or be already set
by default) via sysctl (see kernel.sched_deadline_period_max_us and
kernel.sched_deadline_period_min_us).
All the three parameters are mandatory but period can be set to 0,
in which case it will set to the same value of deadline.
Signed-off-by: Sasha Algisi <sasha.algisi at edu.unito.it>
Signed-off-by: Dario Faggioli <dfaggioli at suse.com>
---
src/ch/ch_process.c | 3 +-
src/conf/domain_conf.h | 3 ++
src/qemu/qemu_process.c | 8 +++-
src/util/virprocess.c | 84 +++++++++++++++++++++++++++++++++++++++--
src/util/virprocess.h | 6 ++-
5 files changed, 97 insertions(+), 7 deletions(-)
diff --git a/src/ch/ch_process.c b/src/ch/ch_process.c
index 77f55e777b..a40d188aac 100644
--- a/src/ch/ch_process.c
+++ b/src/ch/ch_process.c
@@ -293,7 +293,8 @@ virCHProcessSetupPid(virDomainObj *vm,
/* Set scheduler type and priority, but not for the main thread. */
if (sched &&
nameval != VIR_CGROUP_THREAD_EMULATOR &&
- virProcessSetScheduler(pid, sched->policy, sched->priority) < 0)
+ virProcessSetScheduler(pid, sched->policy, sched->priority,
+ sched->runtime, sched->deadline, sched->period) < 0)
goto cleanup;
ret = 0;
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index 060c395943..c3d1a1b65d 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -2454,6 +2454,9 @@ typedef enum {
struct _virDomainThreadSchedParam {
virProcessSchedPolicy policy;
int priority;
+ uint64_t runtime;
+ uint64_t deadline;
+ uint64_t period;
};
struct _virDomainTimerCatchupDef {
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index 137dcf5cf4..7586e0538a 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -2728,7 +2728,8 @@ qemuProcessSetupPid(virDomainObj *vm,
/* Set scheduler type and priority, but not for the main thread. */
if (sched &&
nameval != VIR_CGROUP_THREAD_EMULATOR &&
- virProcessSetScheduler(pid, sched->policy, sched->priority) < 0)
+ virProcessSetScheduler(pid, sched->policy, sched->priority,
+ sched->runtime, sched->deadline, sched->period) < 0)
goto cleanup;
ret = 0;
@@ -7813,7 +7814,10 @@ qemuProcessLaunch(virConnectPtr conn,
if (vm->def->cputune.emulatorsched &&
virProcessSetScheduler(vm->pid,
vm->def->cputune.emulatorsched->policy,
- vm->def->cputune.emulatorsched->priority) < 0)
+ vm->def->cputune.emulatorsched->priority,
+ vm->def->cputune.emulatorsched->runtime,
+ vm->def->cputune.emulatorsched->deadline,
+ vm->def->cputune.emulatorsched->period) < 0)
goto cleanup;
VIR_DEBUG("Setting any required VM passwords");
diff --git a/src/util/virprocess.c b/src/util/virprocess.c
index a8f86784e1..c96bfc45fd 100644
--- a/src/util/virprocess.c
+++ b/src/util/virprocess.c
@@ -84,6 +84,7 @@ VIR_ENUM_IMPL(virProcessSchedPolicy,
"idle",
"fifo",
"rr",
+ "deadline",
);
@@ -1610,6 +1611,13 @@ virProcessSchedTranslatePolicy(virProcessSchedPolicy policy)
case VIR_PROC_POLICY_RR:
return SCHED_RR;
+ case VIR_PROC_POLICY_DEADLINE:
+# ifdef SCHED_DEADLINE
+ return SCHED_DEADLINE;
+# else
+ return -1;
+# endif
+
case VIR_PROC_POLICY_LAST:
/* nada */
break;
@@ -1621,13 +1629,20 @@ virProcessSchedTranslatePolicy(virProcessSchedPolicy policy)
int
virProcessSetScheduler(pid_t pid,
virProcessSchedPolicy policy,
- int priority)
+ int priority,
+ uint64_t runtime G_GNUC_UNUSED,
+ uint64_t deadline G_GNUC_UNUSED,
+ uint64_t period G_GNUC_UNUSED)
{
struct sched_param param = {0};
int pol = virProcessSchedTranslatePolicy(policy);
- VIR_DEBUG("pid=%lld, policy=%d, priority=%u",
- (long long) pid, policy, priority);
+ VIR_DEBUG("pid=%lld, policy=%d, priority=%u, "
+ "runtime=%llu, deadline=%llu, period=%llu",
+ (long long) pid, policy, priority,
+ (unsigned long long) runtime,
+ (unsigned long long) deadline,
+ (unsigned long long) period);
if (!policy)
return 0;
@@ -1667,6 +1682,69 @@ virProcessSetScheduler(pid_t pid,
param.sched_priority = priority;
}
+# ifdef SCHED_DEADLINE
+ if (pol == SCHED_DEADLINE) {
+ struct sched_attr attr = {0};
+ /*
+ * The range is enforced in the kernel.
+ * See: https://man7.org/linux/man-pages/man7/sched.7.html
+ */
+ uint64_t min_value = 1024;
+ uint64_t max_value = (1ULL << 63) - 1;
+
+ if (runtime < min_value || runtime > max_value) {
+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+ _("Scheduler runtime %llu out of range "
+ "[%llu, %llu]"),
+ (unsigned long long) runtime,
+ (unsigned long long) min_value,
+ (unsigned long long) max_value);
+ return -1;
+ }
+
+ if (deadline < runtime || deadline > max_value) {
+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+ _("Scheduler deadline %llu out of range "
+ "[%llu, %llu]"),
+ (unsigned long long) deadline,
+ (unsigned long long) runtime,
+ (unsigned long long) max_value);
+ return -1;
+ }
+
+ if ((period < deadline || period > max_value) && period != 0) {
+ virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+ _("Invalid scheduler period %llu, "
+ "possible correct values are 0 "
+ "or [%llu, %llu]"),
+ (unsigned long long) period,
+ (unsigned long long) deadline,
+ (unsigned long long) max_value);
+ return -1;
+ }
+
+ attr.size = sizeof(attr);
+ attr.sched_policy = pol;
+ /*
+ * Setting reset-on-fork is necessary as SCHED_DEADLINE
+ * tasks cannot fork. See:
+ * https://docs.kernel.org/scheduler/sched-deadline.html#default-behavior
+ */
+ attr.sched_flags = SCHED_FLAG_RESET_ON_FORK;
+ attr.sched_runtime = runtime;
+ attr.sched_deadline = deadline;
+ attr.sched_period = period;
+
+ if (sched_setattr(pid, &attr, 0) == 0) {
+ return 0;
+ } else {
+ virReportSystemError(errno,
+ _("Cannot set scheduler parameters for pid %lld"),
+ (long long) pid);
+ return -1;
+ }
+ }
+# endif
if (sched_setscheduler(pid, pol, ¶m) < 0) {
virReportSystemError(errno,
_("Cannot set scheduler parameters for pid %lld"),
diff --git a/src/util/virprocess.h b/src/util/virprocess.h
index 30b6981c73..84fdf00fdf 100644
--- a/src/util/virprocess.h
+++ b/src/util/virprocess.h
@@ -33,6 +33,7 @@ typedef enum {
VIR_PROC_POLICY_IDLE,
VIR_PROC_POLICY_FIFO,
VIR_PROC_POLICY_RR,
+ VIR_PROC_POLICY_DEADLINE,
VIR_PROC_POLICY_LAST
} virProcessSchedPolicy;
@@ -116,7 +117,10 @@ int virProcessSetupPrivateMountNS(void);
int virProcessSetScheduler(pid_t pid,
virProcessSchedPolicy policy,
- int priority);
+ int priority,
+ uint64_t runtime,
+ uint64_t deadline,
+ uint64_t period);
GStrv virProcessGetStat(pid_t pid, pid_t tid);
--
2.37.1
--
------------------------
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