parisc: Improve cache flushing under qemu

Commit Message

Helge Deller Feb. 13, 2018, 10:10 p.m. UTC

In QEMU we emulate a machine without any data or instruction caches.
Avoid calling the assembly cache flush functions when we have no caches
improves speed with qemu a lot.

Signed-off-by: Helge Deller <[e-mail]>

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Patch

diff --git a/arch/parisc/kernel/cache.c b/arch/parisc/kernel/cache.c
index d5381b3e8f95..b4b6f6631d3b 100644
--- a/arch/parisc/kernel/cache.c
+++ b/arch/parisc/kernel/cache.c
@@ -55,11 +55,17 @@  static struct pdc_btlb_info btlb_info __read_mostly;
 void
 flush_data_cache(void)
 {
+	if (unlikely(!cache_info.dc_size))
+		return;
+
 	on_each_cpu(flush_data_cache_local, NULL, 1);
 }
 void 
 flush_instruction_cache(void)
 {
+	if (unlikely(!cache_info.ic_size))
+		return;
+
 	on_each_cpu(flush_instruction_cache_local, NULL, 1);
 }
 #endif
@@ -67,8 +73,10 @@  flush_instruction_cache(void)
 void
 flush_cache_all_local(void)
 {
-	flush_instruction_cache_local(NULL);
-	flush_data_cache_local(NULL);
+	if (likely(cache_info.ic_size))
+		flush_instruction_cache_local(NULL);
+	if (likely(cache_info.dc_size))
+		flush_data_cache_local(NULL);
 }
 EXPORT_SYMBOL(flush_cache_all_local);
 
@@ -506,7 +515,8 @@  static void cacheflush_h_tmp_function(void *dummy)
 
 void flush_cache_all(void)
 {
-	on_each_cpu(cacheflush_h_tmp_function, NULL, 1);
+	if (likely(cache_info.dc_size || cache_info.ic_size))
+		on_each_cpu(cacheflush_h_tmp_function, NULL, 1);
 }
 
 static inline unsigned long mm_total_size(struct mm_struct *mm)