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[IA64] Avoid unnecessary TLB flushes when allocating memory

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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 <ddd@hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
de Dinechin, Christophe (Integrity VM) 2007-12-13 15:03:07 +00:00 committed by Tony Luck
parent 3cdc7fc7fd
commit aec103bfa6
1 changed files with 15 additions and 3 deletions
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18
arch/ia64/mm/tlb.c
View file

@ -10,6 +10,7 @@
* IPI based ptc implementation and A-step IPI implementation.
* Rohit Seth <rohit.seth@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/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