The 'smt_enabled=X' boot option does not handle values of X > 2.
For Power 7 processors with smt modes of 0,1,2,3, and 4 this does
not work. This patch allows the smt_enabled option to be set to
any value limited to a max equal to the number of threads per
core.
Signed-off-by: Nathan Fontenot <nf...@austin.ibm.com>
---
arch/powerpc/kernel/setup_64.c | 61 ++++++++++++++++++++---------------
arch/powerpc/platforms/pseries/smp.c | 11 ++++--
2 files changed, 42 insertions(+), 30 deletions(-)
Index: powerpc/arch/powerpc/kernel/setup_64.c
===================================================================
--- powerpc.orig/arch/powerpc/kernel/setup_64.c 2010-08-05 10:57:04.000000000
-0500
+++ powerpc/arch/powerpc/kernel/setup_64.c 2010-08-05 11:20:49.000000000
-0500
@@ -95,7 +95,7 @@ int ucache_bsize;
#ifdef CONFIG_SMP
-static int smt_enabled_cmdline;
+static char *smt_enabled_cmdline;
/* Look for ibm,smt-enabled OF option */
static void check_smt_enabled(void)
@@ -103,37 +103,46 @@ static void check_smt_enabled(void)
struct device_node *dn;
const char *smt_option;
- /* Allow the command line to overrule the OF option */
- if (smt_enabled_cmdline)
- return;
-
- dn = of_find_node_by_path("/options");
+ /* Default to enabling all threads */
+ smt_enabled_at_boot = threads_per_core;
- if (dn) {
- smt_option = of_get_property(dn, "ibm,smt-enabled", NULL);
+ /* Allow the command line to overrule the OF option */
+ if (smt_enabled_cmdline) {
+ if (!strcmp(smt_enabled_cmdline, "on"))
+ smt_enabled_at_boot = threads_per_core;
+ else if (!strcmp(smt_enabled_cmdline, "off"))
+ smt_enabled_at_boot = 0;
+ else {
+ long smt;
+ int rc;
+
+ rc = strict_strtol(smt_enabled_cmdline, 10, &smt);
+ if (!rc)
+ smt_enabled_at_boot =
+ min(threads_per_core, (int)smt);
+ }
+ } else {
+ dn = of_find_node_by_path("/options");
+ if (dn) {
+ smt_option = of_get_property(dn, "ibm,smt-enabled",
+ NULL);
+
+ if (smt_option) {
+ if (!strcmp(smt_option, "on"))
+ smt_enabled_at_boot = threads_per_core;
+ else if (!strcmp(smt_option, "off"))
+ smt_enabled_at_boot = 0;
+ }
- if (smt_option) {
- if (!strcmp(smt_option, "on"))
- smt_enabled_at_boot = 1;
- else if (!strcmp(smt_option, "off"))
- smt_enabled_at_boot = 0;
- }
- }
+ of_node_put(dn);
+ }
+ }
}
/* Look for smt-enabled= cmdline option */
static int __init early_smt_enabled(char *p)
{
- smt_enabled_cmdline = 1;
-
- if (!p)
- return 0;
-
- if (!strcmp(p, "on") || !strcmp(p, "1"))
- smt_enabled_at_boot = 1;
- else if (!strcmp(p, "off") || !strcmp(p, "0"))
- smt_enabled_at_boot = 0;
-
+ smt_enabled_cmdline = p;
return 0;
}
early_param("smt-enabled", early_smt_enabled);
@@ -390,8 +399,8 @@ void __init setup_system(void)
*/
xmon_setup();
- check_smt_enabled();
smp_setup_cpu_maps();
+ check_smt_enabled();
#ifdef CONFIG_SMP
/* Release secondary cpus out of their spinloops at 0x60 now that
Index: powerpc/arch/powerpc/platforms/pseries/smp.c
===================================================================
--- powerpc.orig/arch/powerpc/platforms/pseries/smp.c 2010-06-14
08:36:05.000000000 -0500
+++ powerpc/arch/powerpc/platforms/pseries/smp.c 2010-08-05
11:20:49.000000000 -0500
@@ -182,10 +182,13 @@ static int smp_pSeries_cpu_bootable(unsi
/* Special case - we inhibit secondary thread startup
* during boot if the user requests it.
*/
- if (system_state < SYSTEM_RUNNING &&
- cpu_has_feature(CPU_FTR_SMT) &&
- !smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)
- return 0;
+ if (system_state < SYSTEM_RUNNING && cpu_has_feature(CPU_FTR_SMT)) {
+ if (!smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)
+ return 0;
+ if (smt_enabled_at_boot
+ && cpu_thread_in_core(nr) >= smt_enabled_at_boot)
+ return 0;
+ }
return 1;
}
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