Improve performance of memory allocations on ia64 by avoiding a global TLB purge to purge a single page from the file cache. This happens whenever we evict a page from the buffer cache to make room for some other allocation.
Test case: Run 'find /usr -type f | xargs cat > /dev/null' in the background to fill the buffer cache, then run something that uses memory, e.g. 'gmake -j50 install'. Instrumentation showed that the number of global TLB purges went from a few millions down to about 170 over a 12 hours run of the above.
The performance impact is particularly noticeable under virtualization, because a virtual TLB is generally both larger and slower to purge than a physical one.
Signed-off-by: Christophe de Dinechin <[email protected]>
---
diff --git a/arch/ia64/mm/tlb.c b/arch/ia64/mm/tlb.c
index 1682fc6..66ae9c4 100644
--- a/arch/ia64/mm/tlb.c
+++ b/arch/ia64/mm/tlb.c
@@ -10,6 +10,7 @@
* IPI based ptc implementation and A-step IPI implementation.
* Rohit Seth <[email protected]>
* Ken Chen <[email protected]>
+ * Christophe de Dinechin <[email protected]>: Avoid ptc.e on memory allocation
*/
#include <linux/module.h>
#include <linux/init.h>
@@ -89,9 +90,16 @@ ia64_global_tlb_purge (struct mm_struct *mm, unsigned long start,
{
static DEFINE_SPINLOCK(ptcg_lock);
- if (mm != current->active_mm || !current->mm) {
- flush_tlb_all();
- return;
+ struct mm_struct *active_mm = current->active_mm;
+
+ if (mm != active_mm) {
+ /* Restore region IDs for mm */
+ if (mm && active_mm) {
+ activate_context(mm);
+ } else {
+ flush_tlb_all();
+ return;
+ }
}
/* HW requires global serialization of ptc.ga. */
@@ -107,6 +115,10 @@ ia64_global_tlb_purge (struct mm_struct *mm, unsigned long start,
} while (start < end);
}
spin_unlock(&ptcg_lock);
+
+ if (mm != active_mm) {
+ activate_context(active_mm);
+ }
}
void
--
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