sparc64: Add tsb-ratio sysctl.

[karo-tx-linux.git] / arch / sparc / mm / tsb.c

diff --git a/arch/sparc/mm/tsb.c b/arch/sparc/mm/tsb.c
index f0282fad632a40e367b596b9025315230c6494cf..36a0813f9517b39ec9b7b86c17a03233d442483e 100644 (file)
--- 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;