[RFC] [PATCH] Add more info to /proc/$pid/smaps

[RFC] [PATCH] Add more info to /proc/$pid/smaps

[Maxim Levitsky]

I was trying to write a small application similar to pmap, but more powerful.
During the writing I noticed that there are two things I can't get by parsing /proc/$pid/smaps:

1) amount of anonymous memory in a mapping:

It is easy to get it for shared and anonymous mappings (0 for the former, and whole mapping for the latter)
But it is impossible to get it for private writable file mappings.

It seems that the dirty (Private_Dirty+Shared_Dirty) pages amount should indicate number of anonymous pages in the mapping
but this is not the case.

If a dirty page gets swapped, and then brought back due to read access, it will be marked clean, although it is an anonymous page.

2) amount of swapped memory in a mapping:

Again it seems that I can do (Mapping size - RSS) to get amount of memory swapped, but this isn't true too, since
some memory can be untouched , thus be non-present, and non-swapped.


The patch below adds two fields to /proc/$pid/smaps, that give this information.

Probably even more info will be interesting.
How about adding amount of locked memory, and most importantly map count?
This way I can estimate how 'shared' a process memory really is.

Suggestions are welcome.

Best regards,
	Maxim Levitsky

Re: [RFC] [PATCH] Add more info to /proc/$pid/smaps

[Maxim Levitsky]

>From 145247b8e776b32c9930018ab65bb6c5401e28ef Mon Sep 17 00:00:00 2001
From: Maxim Levitsky <maximlevitsky@gmail.com>
Date: Fri, 5 Oct 2007 08:04:03 +0200
Subject: [PATCH] Add more statistics to /proc/$pid/smaps

Add amount of swapped memory and amount of anonymous memory
to /proc/$pid/smaps

Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
---
 fs/proc/task_mmu.c |   18 ++++++++++++++++--
 1 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index c24d81a..1c16a7e 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -122,6 +122,9 @@ struct mem_size_stats
 	unsigned long private_clean;
 	unsigned long private_dirty;
 	unsigned long referenced;
+	unsigned long swapped;
+	unsigned long anon;
+
 };
 
 struct pmd_walker {
@@ -195,6 +198,8 @@ static int show_map_internal(struct seq_file *m, void *v, struct mem_size_stats
 		seq_printf(m,
 			   "Size:           %8lu kB\n"
 			   "Rss:            %8lu kB\n"
+			   "Swapped:        %8lu kB\n"
+			   "Anonymous:      %8lu kB\n"
 			   "Shared_Clean:   %8lu kB\n"
 			   "Shared_Dirty:   %8lu kB\n"
 			   "Private_Clean:  %8lu kB\n"
@@ -202,6 +207,8 @@ static int show_map_internal(struct seq_file *m, void *v, struct mem_size_stats
 			   "Referenced:     %8lu kB\n",
 			   (vma->vm_end - vma->vm_start) >> 10,
 			   mss->resident >> 10,
+			   mss->swapped >> 10,
+			   mss->anon >> 10,
 			   mss->shared_clean  >> 10,
 			   mss->shared_dirty  >> 10,
 			   mss->private_clean >> 10,
@@ -230,15 +237,22 @@ static void smaps_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
 	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
 	for (; addr != end; pte++, addr += PAGE_SIZE) {
 		ptent = *pte;
-		if (!pte_present(ptent))
-			continue;
+		if (!pte_present(ptent)) {
 
+			if(pte_none(ptent) || pte_file(ptent))
+				continue;
+			mss->swapped += PAGE_SIZE;
+			continue;
+		}
 		mss->resident += PAGE_SIZE;
 
 		page = vm_normal_page(vma, addr, ptent);
 		if (!page)
 			continue;
 
+		if(PageAnon(page))
+			mss->anon += PAGE_SIZE;
+
 		/* Accumulate the size in pages that have been accessed. */
 		if (pte_young(ptent) || PageReferenced(page))
 			mss->referenced += PAGE_SIZE;
-- 
1.5.2.5