Author: kib
Date: Tue Apr 24 20:49:16 2018
New Revision: 332973
URL: https://svnweb.freebsd.org/changeset/base/332973
Log:
Make the sysctl machdep.idle also a tunable.
It is applied before it is possible for idle threads to execute on any
CPU, allowing to work around against some bugs.
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Modified:
head/sys/x86/x86/cpu_machdep.c
Modified: head/sys/x86/x86/cpu_machdep.c
==============================================================================
--- head/sys/x86/x86/cpu_machdep.c Tue Apr 24 20:33:08 2018
(r332972)
+++ head/sys/x86/x86/cpu_machdep.c Tue Apr 24 20:49:16 2018
(r332973)
@@ -636,13 +636,33 @@ idle_sysctl_available(SYSCTL_HANDLER_ARGS)
SYSCTL_PROC(_machdep, OID_AUTO, idle_available, CTLTYPE_STRING | CTLFLAG_RD,
0, 0, idle_sysctl_available, "A", "list of available idle functions");
+static bool
+idle_selector(const char *new_idle_name)
+{
+ int i;
+
+ for (i = 0; idle_tbl[i].id_name != NULL; i++) {
+ if (strstr(idle_tbl[i].id_name, "mwait") &&
+ (cpu_feature2 & CPUID2_MON) == 0)
+ continue;
+ if (strcmp(idle_tbl[i].id_name, "acpi") == 0 &&
+ cpu_idle_hook == NULL)
+ continue;
+ if (strcmp(idle_tbl[i].id_name, new_idle_name))
+ continue;
+ cpu_idle_fn = idle_tbl[i].id_fn;
+ if (bootverbose)
+ printf("CPU idle set to %s\n", idle_tbl[i].id_name);
+ return (true);
+ }
+ return (false);
+}
+
static int
idle_sysctl(SYSCTL_HANDLER_ARGS)
{
- char buf[16];
- int error;
- char *p;
- int i;
+ char buf[16], *p;
+ int error, i;
p = "unknown";
for (i = 0; idle_tbl[i].id_name != NULL; i++) {
@@ -655,23 +675,21 @@ idle_sysctl(SYSCTL_HANDLER_ARGS)
error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
if (error != 0 || req->newptr == NULL)
return (error);
- for (i = 0; idle_tbl[i].id_name != NULL; i++) {
- if (strstr(idle_tbl[i].id_name, "mwait") &&
- (cpu_feature2 & CPUID2_MON) == 0)
- continue;
- if (strcmp(idle_tbl[i].id_name, "acpi") == 0 &&
- cpu_idle_hook == NULL)
- continue;
- if (strcmp(idle_tbl[i].id_name, buf))
- continue;
- cpu_idle_fn = idle_tbl[i].id_fn;
- return (0);
- }
- return (EINVAL);
+ return (idle_selector(buf) ? 0 : EINVAL);
}
SYSCTL_PROC(_machdep, OID_AUTO, idle, CTLTYPE_STRING | CTLFLAG_RW, 0, 0,
idle_sysctl, "A", "currently selected idle function");
+
+static void
+idle_tun(void *unused __unused)
+{
+ char tunvar[16];
+
+ if (TUNABLE_STR_FETCH("machdep.idle", tunvar, sizeof(tunvar)))
+ idle_selector(tunvar);
+}
+SYSINIT(idle_tun, SI_SUB_CPU, SI_ORDER_MIDDLE, idle_tun, NULL);
static int panic_on_nmi = 1;
SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RWTUN,
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