[IA64] Kernel parameter for max number of concurrent global TLB purges
The patch defines kernel parameter "nptcg=". The parameter overrides max number
of concurrent global TLB purges which is reported from either PAL_VM_SUMMARY or
SAL PALO.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/kernel/efi.c b/arch/ia64/kernel/efi.c
index 003cd09..d45f215 100644
--- a/arch/ia64/kernel/efi.c
+++ b/arch/ia64/kernel/efi.c
@@ -436,7 +436,7 @@
return;
}
- setup_ptcg_sem(palo->max_tlb_purges, 1);
+ setup_ptcg_sem(palo->max_tlb_purges, NPTCG_FROM_PALO);
}
void
diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
index 1cbd2634..f798c07 100644
--- a/arch/ia64/kernel/setup.c
+++ b/arch/ia64/kernel/setup.c
@@ -949,7 +949,7 @@
/* set ia64_ctx.max_rid to the maximum RID that is supported by all CPUs: */
if (ia64_pal_vm_summary(NULL, &vmi) == 0) {
max_ctx = (1U << (vmi.pal_vm_info_2_s.rid_size - 3)) - 1;
- setup_ptcg_sem(vmi.pal_vm_info_2_s.max_purges, 0);
+ setup_ptcg_sem(vmi.pal_vm_info_2_s.max_purges, NPTCG_FROM_PAL);
} else {
printk(KERN_WARNING "cpu_init: PAL VM summary failed, assuming 18 RID bits\n");
max_ctx = (1U << 15) - 1; /* use architected minimum */
diff --git a/arch/ia64/mm/tlb.c b/arch/ia64/mm/tlb.c
index d41d607..1a8948f 100644
--- a/arch/ia64/mm/tlb.c
+++ b/arch/ia64/mm/tlb.c
@@ -120,19 +120,45 @@
static int toolatetochangeptcgsem = 0;
/*
+ * Kernel parameter "nptcg=" overrides max number of concurrent global TLB
+ * purges which is reported from either PAL or SAL PALO.
+ *
+ * We don't have sanity checking for nptcg value. It's the user's responsibility
+ * for valid nptcg value on the platform. Otherwise, kernel may hang in some
+ * cases.
+ */
+static int __init
+set_nptcg(char *str)
+{
+ int value = 0;
+
+ get_option(&str, &value);
+ setup_ptcg_sem(value, NPTCG_FROM_KERNEL_PARAMETER);
+
+ return 1;
+}
+
+__setup("nptcg=", set_nptcg);
+
+/*
* Maximum number of simultaneous ptc.g purges in the system can
* be defined by PAL_VM_SUMMARY (in which case we should take
* the smallest value for any cpu in the system) or by the PAL
* override table (in which case we should ignore the value from
* PAL_VM_SUMMARY).
*
+ * Kernel parameter "nptcg=" overrides maximum number of simultanesous ptc.g
+ * purges defined in either PAL_VM_SUMMARY or PAL override table. In this case,
+ * we should ignore the value from either PAL_VM_SUMMARY or PAL override table.
+ *
* Complicating the logic here is the fact that num_possible_cpus()
* isn't fully setup until we start bringing cpus online.
*/
void
-setup_ptcg_sem(int max_purges, int from_palo)
+setup_ptcg_sem(int max_purges, int nptcg_from)
{
- static int have_palo;
+ static int kp_override;
+ static int palo_override;
static int firstcpu = 1;
if (toolatetochangeptcgsem) {
@@ -140,8 +166,18 @@
return;
}
- if (from_palo) {
- have_palo = 1;
+ if (nptcg_from == NPTCG_FROM_KERNEL_PARAMETER) {
+ kp_override = 1;
+ nptcg = max_purges;
+ goto resetsema;
+ }
+ if (kp_override) {
+ need_ptcg_sem = num_possible_cpus() > nptcg;
+ return;
+ }
+
+ if (nptcg_from == NPTCG_FROM_PALO) {
+ palo_override = 1;
/* In PALO max_purges == 0 really means it! */
if (max_purges == 0)
@@ -153,7 +189,7 @@
}
goto resetsema;
}
- if (have_palo) {
+ if (palo_override) {
if (nptcg != PALO_MAX_TLB_PURGES)
need_ptcg_sem = (num_possible_cpus() > nptcg);
return;
