Module Name: src
Committed By: riastradh
Date: Mon Jul 17 13:42:23 UTC 2023
Modified Files:
src/sys/kern: kern_tc.c
Log Message:
timecounter(9): Use an ipi barrier on time_second/uptime rollover.
This way we only need __insn_barrier, not membar_consumer, on the
read side.
To generate a diff of this commit:
cvs rdiff -u -r1.66 -r1.67 src/sys/kern/kern_tc.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/kern_tc.c
diff -u src/sys/kern/kern_tc.c:1.66 src/sys/kern/kern_tc.c:1.67
--- src/sys/kern/kern_tc.c:1.66 Mon Jul 17 13:42:02 2023
+++ src/sys/kern/kern_tc.c Mon Jul 17 13:42:23 2023
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_tc.c,v 1.66 2023/07/17 13:42:02 riastradh Exp $ */
+/* $NetBSD: kern_tc.c,v 1.67 2023/07/17 13:42:23 riastradh Exp $ */
/*-
* Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
@@ -40,7 +40,7 @@
#include <sys/cdefs.h>
/* __FBSDID("$FreeBSD: src/sys/kern/kern_tc.c,v 1.166 2005/09/19 22:16:31 andre Exp $"); */
-__KERNEL_RCSID(0, "$NetBSD: kern_tc.c,v 1.66 2023/07/17 13:42:02 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_tc.c,v 1.67 2023/07/17 13:42:23 riastradh Exp $");
#ifdef _KERNEL_OPT
#include "opt_ntp.h"
@@ -50,6 +50,7 @@ __KERNEL_RCSID(0, "$NetBSD: kern_tc.c,v
#include <sys/atomic.h>
#include <sys/evcnt.h>
+#include <sys/ipi.h>
#include <sys/kauth.h>
#include <sys/kernel.h>
#include <sys/lock.h>
@@ -167,6 +168,24 @@ setrealuptime(time_t second, time_t upti
#else
+static void
+nullipi(void *cookie)
+{
+}
+
+/*
+ * Issue membar_release on this CPU, and force membar_acquire on all
+ * CPUs.
+ */
+static void
+ipi_barrier(void)
+{
+ ipi_msg_t msg = { .func = nullipi };
+
+ ipi_broadcast(&msg, /*skip_self*/true);
+ ipi_wait(&msg);
+}
+
static inline void
setrealuptime(time_t second, time_t uptime)
{
@@ -188,10 +207,10 @@ setrealuptime(time_t second, time_t upti
atomic_store_relaxed(&time__second32.hi, 0xffffffff);
atomic_store_relaxed(&time__uptime32.hi, 0xffffffff);
- membar_producer();
+ ipi_barrier();
atomic_store_relaxed(&time__second32.lo, seclo);
atomic_store_relaxed(&time__uptime32.lo, uplo);
- membar_producer();
+ ipi_barrier();
atomic_store_relaxed(&time__second32.hi, sechi);
atomic_store_relaxed(&time__uptime32.hi, uphi);
}
@@ -208,9 +227,9 @@ getrealtime(void)
break;
SPINLOCK_BACKOFF_HOOK;
}
- membar_consumer();
+ __insn_barrier();
lo = atomic_load_relaxed(&time__second32.lo);
- membar_consumer();
+ __insn_barrier();
} while (hi != atomic_load_relaxed(&time__second32.hi));
return ((time_t)hi << 32) | lo;
@@ -228,9 +247,9 @@ getuptime(void)
break;
SPINLOCK_BACKOFF_HOOK;
}
- membar_consumer();
+ __insn_barrier();
lo = atomic_load_relaxed(&time__uptime32.lo);
- membar_consumer();
+ __insn_barrier();
} while (hi != atomic_load_relaxed(&time__uptime32.hi));
return ((time_t)hi << 32) | lo;
