Commit aec103bf authored by de Dinechin, Christophe (Integrity VM)'s avatar de Dinechin, Christophe (Integrity VM) Committed by Tony Luck

[IA64] Avoid unnecessary TLB flushes when allocating memory

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: default avatarChristophe de Dinechin <ddd@hp.com>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 3cdc7fc7
...@@ -10,6 +10,7 @@ ...@@ -10,6 +10,7 @@
* IPI based ptc implementation and A-step IPI implementation. * IPI based ptc implementation and A-step IPI implementation.
* Rohit Seth <rohit.seth@intel.com> * Rohit Seth <rohit.seth@intel.com>
* Ken Chen <kenneth.w.chen@intel.com> * Ken Chen <kenneth.w.chen@intel.com>
* Christophe de Dinechin <ddd@hp.com>: Avoid ptc.e on memory allocation
*/ */
#include <linux/module.h> #include <linux/module.h>
#include <linux/init.h> #include <linux/init.h>
...@@ -89,10 +90,17 @@ ia64_global_tlb_purge (struct mm_struct *mm, unsigned long start, ...@@ -89,10 +90,17 @@ ia64_global_tlb_purge (struct mm_struct *mm, unsigned long start,
{ {
static DEFINE_SPINLOCK(ptcg_lock); static DEFINE_SPINLOCK(ptcg_lock);
if (mm != current->active_mm || !current->mm) { 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(); flush_tlb_all();
return; return;
} }
}
/* HW requires global serialization of ptc.ga. */ /* HW requires global serialization of ptc.ga. */
spin_lock(&ptcg_lock); spin_lock(&ptcg_lock);
...@@ -107,6 +115,10 @@ ia64_global_tlb_purge (struct mm_struct *mm, unsigned long start, ...@@ -107,6 +115,10 @@ ia64_global_tlb_purge (struct mm_struct *mm, unsigned long start,
} while (start < end); } while (start < end);
} }
spin_unlock(&ptcg_lock); spin_unlock(&ptcg_lock);
if (mm != active_mm) {
activate_context(active_mm);
}
} }
void void
......
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