git: 179f5b2bfedc - main - sched: fix kern.sched.{4bsd,ule}.slice

The branch main has been updated by mchoo:

URL: https://cgit.FreeBSD.org/src/commit/?id=179f5b2bfedccc762352f06057f4e389bfabb2ea

commit 179f5b2bfedccc762352f06057f4e389bfabb2ea
Author:     Minsoo Choo <mchoo@FreeBSD.org>
AuthorDate: 2026-08-24 02:25:35 +0000
Commit:     Minsoo Choo <mchoo@FreeBSD.org>
CommitDate: 2026-09-18 14:14:13 +0000

    sched: fix kern.sched.{4bsd,ule}.slice
    
    Fix three problems with kern.sched.{4bsd,ule}.slice:
    
     * Guarantee minimum slice is 1.
     * Recalculate hogticks on sysctl write.
     * For ULE, recalculate sched_slice_min on sysctl write.
    
    Reviewed by:    olce
    Approved by:    olce (mentor)
    MFC after:      2 weeks
    Sponsored by:   FreeBSD Foundation
    Differential Revision:  https://reviews.freebsd.org/D59401
---
 sys/kern/sched_4bsd.c | 21 ++++++++++++++++++++-
 sys/kern/sched_ule.c  | 22 +++++++++++++++++++++-
 2 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/sys/kern/sched_4bsd.c b/sys/kern/sched_4bsd.c
index 7965357e072e..4db2364785f6 100644
--- a/sys/kern/sched_4bsd.c
+++ b/sys/kern/sched_4bsd.c
@@ -211,6 +211,23 @@ sysctl_kern_4bsd_quantum(SYSCTL_HANDLER_ARGS)
 	return (0);
 }
 
+static int
+sysctl_kern_slice(SYSCTL_HANDLER_ARGS)
+{
+	int error, new_val;
+
+	new_val = sched_slice;
+	error = sysctl_handle_int(oidp, &new_val, 0, req);
+	if (error != 0 || req->newptr == NULL)
+		return (error);
+	if (new_val <= 0)
+		return (EINVAL);
+	sched_slice = new_val;
+	hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
+	    realstathz);
+	return (0);
+}
+
 SYSCTL_NODE(_kern_sched, OID_AUTO, 4bsd, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
     "4BSD Scheduler");
 
@@ -218,7 +235,9 @@ SYSCTL_PROC(_kern_sched_4bsd, OID_AUTO, quantum,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0,
     sysctl_kern_4bsd_quantum, "I",
     "Quantum for timeshare threads in microseconds");
-SYSCTL_INT(_kern_sched_4bsd, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0,
+SYSCTL_PROC(_kern_sched_4bsd, OID_AUTO, slice,
+    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0,
+    sysctl_kern_slice, "I",
     "Quantum for timeshare threads in stathz ticks");
 #ifdef SMP
 /* Enable forwarding of wakeups to all other cpus */
diff --git a/sys/kern/sched_ule.c b/sys/kern/sched_ule.c
index 6f6b78488253..8217c536d440 100644
--- a/sys/kern/sched_ule.c
+++ b/sys/kern/sched_ule.c
@@ -3484,6 +3484,24 @@ sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
 	return (0);
 }
 
+static int
+sysctl_kern_slice(SYSCTL_HANDLER_ARGS)
+{
+	int error, new_val;
+
+	new_val = sched_slice;
+	error = sysctl_handle_int(oidp, &new_val, 0, req);
+	if (error != 0 || req->newptr == NULL)
+		return (error);
+	if (new_val <= 0)
+		return (EINVAL);
+	sched_slice = new_val;
+	sched_slice_min = imax(1, sched_slice / SCHED_SLICE_MIN_DIVISOR);
+	hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
+	    realstathz);
+	return (0);
+}
+
 SYSCTL_NODE(_kern_sched, OID_AUTO, ule, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
     "ULE Scheduler");
 
@@ -3491,7 +3509,9 @@ SYSCTL_PROC(_kern_sched_ule, OID_AUTO, quantum,
     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0,
     sysctl_kern_quantum, "I",
     "Quantum for timeshare threads in microseconds");
-SYSCTL_INT(_kern_sched_ule, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0,
+SYSCTL_PROC(_kern_sched_ule, OID_AUTO, slice,
+    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0,
+    sysctl_kern_slice, "I",
     "Quantum for timeshare threads in stathz ticks");
 SYSCTL_UINT(_kern_sched_ule, OID_AUTO, interact, CTLFLAG_RWTUN, &sched_interact, 0,
     "Interactivity score threshold");