[RFC MM] swap counters

[Christoph Lameter <cl@linux-foundation.org>]

Kamezawa sans swap counters on top of it all. Now we need no additional
atomic ops in VM fast paths.

---
 fs/proc/task_mmu.c       |   14 +++++++++++---
 include/linux/mm_types.h |    1 +
 mm/memory.c              |   17 +++++++++++++----
 mm/rmap.c                |    1 +
 mm/swapfile.c            |    1 +
 5 files changed, 27 insertions(+), 7 deletions(-)

Index: linux-2.6/fs/proc/task_mmu.c
===================================================================
--- linux-2.6.orig/fs/proc/task_mmu.c	2009-11-05 15:58:48.000000000 -0600
+++ linux-2.6/fs/proc/task_mmu.c	2009-11-05 16:03:12.000000000 -0600
@@ -16,8 +16,9 @@

 void task_mem(struct seq_file *m, struct mm_struct *mm)
 {
-	unsigned long data, text, lib;
+	unsigned long data, text, lib, swap;
 	unsigned long hiwater_vm, total_vm, hiwater_rss, total_rss;
+	int cpu;

 	/*
 	 * Note: to minimize their overhead, mm maintains hiwater_vm and
@@ -36,6 +37,11 @@ void task_mem(struct seq_file *m, struct
 	data = mm->total_vm - mm->shared_vm - mm->stack_vm;
 	text = (PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK)) >> 10;
 	lib = (mm->exec_vm << (PAGE_SHIFT-10)) - text;
+
+	swap = 0;
+	for_each_possible_cpu(cpu)
+		swap += per_cpu(mm->rss->swap, cpu);
+
 	seq_printf(m,
 		"VmPeak:\t%8lu kB\n"
 		"VmSize:\t%8lu kB\n"
@@ -46,7 +52,8 @@ void task_mem(struct seq_file *m, struct
 		"VmStk:\t%8lu kB\n"
 		"VmExe:\t%8lu kB\n"
 		"VmLib:\t%8lu kB\n"
-		"VmPTE:\t%8lu kB\n",
+		"VmPTE:\t%8lu kB\n"
+		"VmSwap:\t%8lu kB\n",
 		hiwater_vm << (PAGE_SHIFT-10),
 		(total_vm - mm->reserved_vm) << (PAGE_SHIFT-10),
 		mm->locked_vm << (PAGE_SHIFT-10),
@@ -54,7 +61,8 @@ void task_mem(struct seq_file *m, struct
 		total_rss << (PAGE_SHIFT-10),
 		data << (PAGE_SHIFT-10),
 		mm->stack_vm << (PAGE_SHIFT-10), text, lib,
-		(PTRS_PER_PTE*sizeof(pte_t)*mm->nr_ptes) >> 10);
+		(PTRS_PER_PTE*sizeof(pte_t)*mm->nr_ptes) >> 10,
+		swap << (PAGE_SHIFT - 10));
 }

 unsigned long task_vsize(struct mm_struct *mm)
Index: linux-2.6/include/linux/mm_types.h
===================================================================
--- linux-2.6.orig/include/linux/mm_types.h	2009-11-05 15:51:38.000000000 -0600
+++ linux-2.6/include/linux/mm_types.h	2009-11-05 15:51:55.000000000 -0600
@@ -28,6 +28,7 @@ struct address_space;
 struct mm_counter {
 	long file;
 	long anon;
+	long swap;
 	long readers;
 };

Index: linux-2.6/mm/memory.c
===================================================================
--- linux-2.6.orig/mm/memory.c	2009-11-05 15:52:00.000000000 -0600
+++ linux-2.6/mm/memory.c	2009-11-05 16:01:48.000000000 -0600
@@ -587,7 +587,9 @@ copy_one_pte(struct mm_struct *dst_mm, s
 						 &src_mm->mmlist);
 				spin_unlock(&mmlist_lock);
 			}
-			if (is_write_migration_entry(entry) &&
+			if (!is_migration_entry(entry))
+				__this_cpu_inc(src_mm->rss->swap);
+			else if (is_write_migration_entry(entry) &&
 					is_cow_mapping(vm_flags)) {
 				/*
 				 * COW mappings require pages in both parent
@@ -864,9 +866,15 @@ static unsigned long zap_pte_range(struc
 		if (pte_file(ptent)) {
 			if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
 				print_bad_pte(vma, addr, ptent, NULL);
-		} else if
-		  (unlikely(!free_swap_and_cache(pte_to_swp_entry(ptent))))
-			print_bad_pte(vma, addr, ptent, NULL);
+		} else {
+			swp_entry_t ent = pte_to_swp_entry(ptent);
+
+			if (!is_migration_entry(ent))
+				__this_cpu_dec(mm->rss->swap);
+
+			if (unlikely(!free_swap_and_cache(ent)))
+				print_bad_pte(vma, addr, ptent, NULL);
+		}
 		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
 	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));

@@ -2569,6 +2577,7 @@ static int do_swap_page(struct mm_struct
 	 */

 	__this_cpu_inc(mm->rss->anon);
+	__this_cpu_dec(mm->rss->swap);
 	pte = mk_pte(page, vma->vm_page_prot);
 	if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
 		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
Index: linux-2.6/mm/rmap.c
===================================================================
--- linux-2.6.orig/mm/rmap.c	2009-11-05 15:57:51.000000000 -0600
+++ linux-2.6/mm/rmap.c	2009-11-05 15:58:43.000000000 -0600
@@ -830,6 +830,7 @@ static int try_to_unmap_one(struct page
 				spin_unlock(&mmlist_lock);
 			}
 			__this_cpu_dec(mm->rss->anon);
+			__this_cpu_inc(mm->rss->swap);
 		} else if (PAGE_MIGRATION) {
 			/*
 			 * Store the pfn of the page in a special migration
Index: linux-2.6/mm/swapfile.c
===================================================================
--- linux-2.6.orig/mm/swapfile.c	2009-11-05 15:57:15.000000000 -0600
+++ linux-2.6/mm/swapfile.c	2009-11-05 15:57:36.000000000 -0600
@@ -832,6 +832,7 @@ static int unuse_pte(struct vm_area_stru
 	}

 	__this_cpu_inc(vma->vm_mm->rss->anon);
+	__this_cpu_dec(vma->vm_mm->rss->swap);
 	get_page(page);
 	set_pte_at(vma->vm_mm, addr, pte,
 		   pte_mkold(mk_pte(page, vma->vm_page_prot)));

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