From: Martin Hicks <mort@wildopensource.com>
This is a patch based on one that Jack Steiner sent to the ia64 list in
November. The original thread can be found at:
http://marc.theaimsgroup.com/?l=linux-ia64&m=106869606922555&w=2
I created the little wrapper function that was requested. I think the only
other arch, other than ia64, that doesn't at least include asm-generic/tlb.h
is arm.
Something appears broken in TLB flushing on IA64 (& possibly other
architectures). Functionally, it works but performance is bad on systems
with large cpu counts.
The result is that TLB flushing in exit_mmap() is frequently being done via
IPIs to all cpus rather than with a "ptc" instruction or with a new
context..
---
include/asm-arm/tlb.h | 6 ++++++
include/asm-generic/tlb.h | 5 +++++
include/asm-ia64/tlb.h | 6 ++++++
mm/memory.c | 3 ++-
4 files changed, 19 insertions(+), 1 deletion(-)
diff -puN include/asm-arm/tlb.h~tlb-flushing-speedup include/asm-arm/tlb.h
--- 25/include/asm-arm/tlb.h~tlb-flushing-speedup 2004-02-16 23:43:20.000000000 -0800
+++ 25-akpm/include/asm-arm/tlb.h 2004-02-16 23:43:20.000000000 -0800
@@ -70,6 +70,12 @@ tlb_finish_mmu(struct mmu_gather *tlb, u
check_pgt_cache();
}
+static inline unsigned int
+tlb_is_full_mm(struct mmu_gather *tlb)
+{
+ return tlb->fullmm;
+}
+
#define tlb_remove_tlb_entry(tlb,ptep,address) do { } while (0)
#define tlb_start_vma(tlb,vma) \
diff -puN include/asm-generic/tlb.h~tlb-flushing-speedup include/asm-generic/tlb.h
--- 25/include/asm-generic/tlb.h~tlb-flushing-speedup 2004-02-16 23:43:20.000000000 -0800
+++ 25-akpm/include/asm-generic/tlb.h 2004-02-16 23:43:20.000000000 -0800
@@ -98,6 +98,11 @@ tlb_finish_mmu(struct mmu_gather *tlb, u
check_pgt_cache();
}
+static inline unsigned int
+tlb_is_full_mm(struct mmu_gather *tlb)
+{
+ return tlb->fullmm;
+}
/* tlb_remove_page
* Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
diff -puN include/asm-ia64/tlb.h~tlb-flushing-speedup include/asm-ia64/tlb.h
--- 25/include/asm-ia64/tlb.h~tlb-flushing-speedup 2004-02-16 23:43:20.000000000 -0800
+++ 25-akpm/include/asm-ia64/tlb.h 2004-02-16 23:43:20.000000000 -0800
@@ -173,6 +173,12 @@ tlb_finish_mmu (struct mmu_gather *tlb,
check_pgt_cache();
}
+static inline unsigned int
+tlb_is_full_mm(struct mmu_gather *tlb)
+{
+ return tlb->fullmm;
+}
+
/*
* Logically, this routine frees PAGE. On MP machines, the actual freeing of the page
* must be delayed until after the TLB has been flushed (see comments at the beginning of
diff -puN mm/memory.c~tlb-flushing-speedup mm/memory.c
--- 25/mm/memory.c~tlb-flushing-speedup 2004-02-16 23:43:20.000000000 -0800
+++ 25-akpm/mm/memory.c 2004-02-16 23:43:20.000000000 -0800
@@ -574,9 +574,10 @@ int unmap_vmas(struct mmu_gather **tlbp,
if ((long)zap_bytes > 0)
continue;
if (need_resched()) {
+ int fullmm = tlb_is_full_mm(*tlbp);
tlb_finish_mmu(*tlbp, tlb_start, start);
cond_resched_lock(&mm->page_table_lock);
- *tlbp = tlb_gather_mmu(mm, 0);
+ *tlbp = tlb_gather_mmu(mm, fullmm);
tlb_start_valid = 0;
}
zap_bytes = ZAP_BLOCK_SIZE;
_