2 files changed, 28 insertions, 7 deletions

diff --git a/arch/sparc/mm/tsb.c b/arch/sparc/mm/tsb.c
index f0282fad632a..36a0813f9517 100644
--- a/arch/sparc/mm/tsb.c
+++ b/arch/sparc/mm/tsb.c
@@ -265,6 +265,18 @@ void __init pgtable_cache_init(void)
         }
 }
 
+int sysctl_tsb_ratio = -2;
+
+static unsigned long tsb_size_to_rss_limit(unsigned long new_size)
+{
+        unsigned long num_ents = (new_size / sizeof(struct tsb));
+
+        if (sysctl_tsb_ratio < 0)
+                return num_ents - (num_ents >> -sysctl_tsb_ratio);
+        else
+                return num_ents + (num_ents >> sysctl_tsb_ratio);
+}
+
 /* When the RSS of an address space exceeds tsb_rss_limit for a TSB,
  * do_sparc64_fault() invokes this routine to try and grow it.
  *
@@ -295,19 +307,14 @@ void tsb_grow(struct mm_struct *mm, unsigned long tsb_index, unsigned long rss)
 
         new_cache_index = 0;
         for (new_size = 8192; new_size < max_tsb_size; new_size <<= 1UL) {
-                unsigned long n_entries = new_size / sizeof(struct tsb);
-
-                n_entries = (n_entries * 3) / 4;
-                if (n_entries > rss)
+                new_rss_limit = tsb_size_to_rss_limit(new_size);
+                if (new_rss_limit > rss)
                         break;
-
                 new_cache_index++;
         }
 
         if (new_size == max_tsb_size)
                 new_rss_limit = ~0UL;
-        else
-                new_rss_limit = ((new_size / sizeof(struct tsb)) * 3) / 4;
 
 retry_tsb_alloc:
         gfp_flags = GFP_KERNEL;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 3d56fe7570da..4e2ac0aec9b0 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -121,6 +121,10 @@ extern int sg_big_buff;
 #include <asm/system.h>
 #endif
 
+#ifdef CONFIG_SPARC64
+extern int sysctl_tsb_ratio;
+#endif
+
 #ifdef __hppa__
 extern int pwrsw_enabled;
 extern int unaligned_enabled;
@@ -451,6 +455,16 @@ static struct ctl_table kern_table[] = {
                 .proc_handler   = &proc_dointvec,
         },
 #endif
+#ifdef CONFIG_SPARC64
+        {
+                .ctl_name       = CTL_UNNUMBERED,
+                .procname       = "tsb-ratio",
+                .data           = &sysctl_tsb_ratio,
+                .maxlen         = sizeof (int),
+                .mode           = 0644,
+                .proc_handler   = &proc_dointvec,
+        },
+#endif
 #ifdef __hppa__
         {
                 .ctl_name       = KERN_HPPA_PWRSW,