core: add CPUQuotaPeriodSec=

This new setting allows configuration of CFS period on the CPU cgroup, instead
of using a hardcoded default of 100ms.

Tested:
- Legacy cgroup + Unified cgroup
- systemctl set-property
- systemctl show
- Confirmed that the cgroup settings (such as cpu.cfs_period_ns) were set
  appropriately, including updating the CPU quota (cpu.cfs_quota_ns) when
  CPUQuotaPeriodSec= is updated.
- Checked that clamping works properly when either period or (quota * period)
  are below the resolution of 1ms, or if period is above the max of 1s.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/core/cgroup.h b/src/core/cgroup.h
index 266daa20a5..42da777c29 100644
--- a/src/core/cgroup.h
+++ b/src/core/cgroup.h
@@ -83,6 +83,7 @@ struct CGroupContext {
         uint64_t cpu_weight;
         uint64_t startup_cpu_weight;
         usec_t cpu_quota_per_sec_usec;
+        usec_t cpu_quota_period_usec;
 
         uint64_t io_weight;
         uint64_t startup_io_weight;
@@ -135,6 +136,8 @@ typedef enum CGroupIPAccountingMetric {
 typedef struct Unit Unit;
 typedef struct Manager Manager;
 
+usec_t cgroup_cpu_adjust_period(usec_t period, usec_t quota, usec_t resolution, usec_t max_period);
+
 void cgroup_context_init(CGroupContext *c);
 void cgroup_context_done(CGroupContext *c);
 void cgroup_context_dump(CGroupContext *c, FILE* f, const char *prefix);