From aec103bfa60e9f72bd66a144236592f54b986a03 Mon Sep 17 00:00:00 2001 From: "de Dinechin, Christophe (Integrity VM)" Date: Thu, 13 Dec 2007 15:03:07 +0000 Subject: [PATCH] [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: Christophe de Dinechin Signed-off-by: Tony Luck --- arch/ia64/mm/tlb.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/arch/ia64/mm/tlb.c b/arch/ia64/mm/tlb.c index cef1647..655da24 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 * Ken Chen + * Christophe de Dinechin : Avoid ptc.e on memory allocation */ #include #include @@ -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 -- 2.7.4