[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/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 4cd1a5da80a4d4f11a17214ed8c344ccf9bd06c4..be92e6165722d0ab437d3de799f8d66fce48dd78 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1335,6 +1335,10 @@ and is between 256 and 4096 characters. It is defined in the file
 
        nowb            [ARM]
 
+       nptcg=          [IA64] Override max number of concurrent global TLB
+                       purges which is reported from either PAL_VM_SUMMARY or
+                       SAL PALO.
+
        numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
                        one of ['zone', 'node', 'default'] can be specified
                        This can be set from sysctl after boot.

diff --git a/arch/ia64/kernel/efi.c b/arch/ia64/kernel/efi.c
index 003cd09b0732cd36f5e244f85909a72fd1ae726a..d45f215bc8fce2ee175d018c8298a506437eb0be 100644 (file)
--- a/arch/ia64/kernel/efi.c
+++ b/arch/ia64/kernel/efi.c
@@ -436,7 +436,7 @@ static void __init handle_palo(unsigned long palo_phys)
                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 1cbd26340d875530449c551db4fcd85a14cd8bcf..f798c0769d360ff79ac4a24295e8b885c1361599 100644 (file)
--- a/arch/ia64/kernel/setup.c
+++ b/arch/ia64/kernel/setup.c
@@ -949,7 +949,7 @@ cpu_init (void)
        /* 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 d41d6076ed03472f80bcf828b4efa96f6c53fb6f..1a8948fd002905c361b17d135292bb1c630a8909 100644 (file)
--- a/arch/ia64/mm/tlb.c
+++ b/arch/ia64/mm/tlb.c
@@ -119,6 +119,27 @@ static u16 nptcg = 1;
 static int need_ptcg_sem = 1;
 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
@@ -126,13 +147,18 @@ static int toolatetochangeptcgsem = 0;
  * 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 @@ setup_ptcg_sem(int max_purges, int from_palo)
                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 @@ setup_ptcg_sem(int max_purges, int from_palo)
                }
                goto resetsema;
        }
-       if (have_palo) {
+       if (palo_override) {
                if (nptcg != PALO_MAX_TLB_PURGES)
                        need_ptcg_sem = (num_possible_cpus() > nptcg);
                return;

diff --git a/include/asm-ia64/sal.h b/include/asm-ia64/sal.h
index 3cd637a2c051577c5326c39b007213f661386daa..89594b442f835e3ff162cc60bd8fdb55f099e641 100644 (file)
--- a/include/asm-ia64/sal.h
+++ b/include/asm-ia64/sal.h
@@ -896,6 +896,10 @@ struct palo_table {
        u8  reserved2[6];
 };
 
+#define NPTCG_FROM_PAL                 0
+#define NPTCG_FROM_PALO                        1
+#define NPTCG_FROM_KERNEL_PARAMETER    2
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_IA64_SAL_H */