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Make the sysctl machdep.idle also a tunable.

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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
This commit is contained in:
Konstantin Belousov 2018-04-24 20:49:16 +00:00
parent bc7e39c339
commit 55ba21d4fd
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=332973
1 changed files with 35 additions and 17 deletions
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52
sys/x86/x86/cpu_machdep.c
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@ -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++) {
@ -655,24 +675,22 @@ 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,
&panic_on_nmi, 0,