[PATCH] i386: Use CLFLUSH instead of WBINVD in change_page_attr

CLFLUSH is a lot faster than WBINVD so try to use that.

Signed-off-by: Andi Kleen <ak@suse.de>

2 files changed, 18 insertions, 7 deletions

diff --git a/arch/i386/mm/pageattr.c b/arch/i386/mm/pageattr.c
index 8564b6ae17e..ad91528bdc1 100644
--- a/arch/i386/mm/pageattr.c
+++ b/arch/i386/mm/pageattr.c
@@ -67,11 +67,17 @@ static struct page *split_large_page(unsigned long address, pgprot_t prot,
         return base;
 } 
 
-static void flush_kernel_map(void *dummy) 
+static void flush_kernel_map(void *arg)
 { 
-        /* Could use CLFLUSH here if the CPU supports it (Hammer,P4) */
-        if (boot_cpu_data.x86_model >= 4) 
+        unsigned long adr = (unsigned long)arg;
+
+        if (adr && cpu_has_clflush) {
+                int i;
+                for (i = 0; i < PAGE_SIZE; i += boot_cpu_data.x86_clflush_size)
+                        asm volatile("clflush (%0)" :: "r" (adr + i));
+        } else if (boot_cpu_data.x86_model >= 4)
                 wbinvd();
+
         /* Flush all to work around Errata in early athlons regarding 
          * large page flushing. 
          */
@@ -173,9 +179,9 @@ __change_page_attr(struct page *page, pgprot_t prot)
         return 0;
 } 
 
-static inline void flush_map(void)
+static inline void flush_map(void *adr)
 {
-        on_each_cpu(flush_kernel_map, NULL, 1, 1);
+        on_each_cpu(flush_kernel_map, adr, 1, 1);
 }
 
 /*
@@ -217,9 +223,13 @@ void global_flush_tlb(void)
         spin_lock_irq(&cpa_lock);
         list_replace_init(&df_list, &l);
         spin_unlock_irq(&cpa_lock);
-        flush_map();
-        list_for_each_entry_safe(pg, next, &l, lru)
+        if (!cpu_has_clflush)
+                flush_map(0);
+        list_for_each_entry_safe(pg, next, &l, lru) {
+                if (cpu_has_clflush)
+                        flush_map(page_address(pg));
                 __free_page(pg);
+        }
 }
 
 #ifdef CONFIG_DEBUG_PAGEALLOC
diff --git a/include/asm-i386/cpufeature.h b/include/asm-i386/cpufeature.h
index 231672558c1..4c83e059228 100644
--- a/include/asm-i386/cpufeature.h
+++ b/include/asm-i386/cpufeature.h
@@ -137,6 +137,7 @@
 #define cpu_has_pmm_enabled     boot_cpu_has(X86_FEATURE_PMM_EN)
 #define cpu_has_ds              boot_cpu_has(X86_FEATURE_DS)
 #define cpu_has_pebs            boot_cpu_has(X86_FEATURE_PEBS)
+#define cpu_has_clflush         boot_cpu_has(X86_FEATURE_CLFLSH)
 
 #endif /* __ASM_I386_CPUFEATURE_H */