From 96355c79a38032ab4bd880b3b3ff4192ae709795 Mon Sep 17 00:00:00 2001
From: Paul Buetow <paul@buetow.org>
Date: Wed, 20 May 2026 14:37:41 +0300
Subject: task 27: add KindSleep and requested sleep metric

---
 cmd/ioworkload/scenario_sleep.go | 45 ++++++++++++++++++++++++++++++++++++++++
 cmd/ioworkload/scenarios.go      |  1 +
 2 files changed, 46 insertions(+)
 create mode 100644 cmd/ioworkload/scenario_sleep.go

(limited to 'cmd')

diff --git a/cmd/ioworkload/scenario_sleep.go b/cmd/ioworkload/scenario_sleep.go
new file mode 100644
index 0000000..bb6c5a4
--- /dev/null
+++ b/cmd/ioworkload/scenario_sleep.go
@@ -0,0 +1,45 @@
+package main
+
+import (
+	"fmt"
+	"runtime"
+	"syscall"
+	"time"
+	"unsafe"
+
+	"golang.org/x/sys/unix"
+)
+
+const sleepSyscallsEmitFor = 2 * time.Second
+
+func sleepSyscalls() error {
+	deadline := time.Now().Add(sleepSyscallsEmitFor)
+	for time.Now().Before(deadline) {
+		if err := syscall.Nanosleep(&syscall.Timespec{Sec: 0, Nsec: 2_000_000}, nil); err != nil && err != syscall.EINTR {
+			return fmt.Errorf("nanosleep: %w", err)
+		}
+		if err := callClockNanosleep(3_000_000); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func callClockNanosleep(requestedNs int64) error {
+	req := unix.Timespec{Sec: requestedNs / 1_000_000_000, Nsec: requestedNs % 1_000_000_000}
+	_, _, errno := syscall.RawSyscall6(
+		unix.SYS_CLOCK_NANOSLEEP,
+		uintptr(unix.CLOCK_MONOTONIC),
+		0,
+		uintptr(unsafe.Pointer(&req)),
+		0,
+		0,
+		0,
+	)
+	runtime.KeepAlive(req)
+	if errno != 0 && errno != syscall.EINTR {
+		return fmt.Errorf("clock_nanosleep: %w", errno)
+	}
+	return nil
+}
+
diff --git a/cmd/ioworkload/scenarios.go b/cmd/ioworkload/scenarios.go
index 8f4eef2..e0827a5 100644
--- a/cmd/ioworkload/scenarios.go
+++ b/cmd/ioworkload/scenarios.go
@@ -35,6 +35,7 @@ var scenarios = map[string]func() error{
 	"eventfd-basic":                 eventfdBasic,
 	"eventfd2-basic":                eventfd2Basic,
 	"polling-epoll":                 pollingEpoll,
+	"sleep-syscalls":                sleepSyscalls,
 	"family-mixed":                  familyMixed,
 	"close-basic":                   closeBasic,
 	"close-range":                   closeRange,
-- 
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