parisc: Improve cache flushing under qemu

PATCH New Helge Deller 1 participant 1 message Feb 13, 2018 PA-RISC architecture

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Helge Deller

author maintainer

2018-02-13 22:10 UTC #0 lore raw

PATCH 1/1 parisc: Improve cache flushing under qemu

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 <[email protected]>

arch/parisc/kernel/cache.c +12 -3

index d5381b3e8f95..b4b6f6631d3b 100644
@@ -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)