The "proportional set size" (PSS) of a process is the count of pages it has in
memory, where each page is divided by the number of processes sharing it. So if
a process has 1000 pages all to itself, and 1000 shared with one other process,
its PSS will be 1500.
- lwn.net: "ELC: How much memory are applications really using?"
The PSS proposed by Matt Mackall is a very nice metic for measuring an process's
memory footprint. So collect and export it via /proc/<pid>/smaps.
Matt Mackall's pagemap/kpagemap and John Berthels's exmap can also do the job,
providing pretty much details. But for PSS, let's do it in a simple way.
Cc: Matt Mackall <[email protected]>
Cc: John Berthels <[email protected]>
Signed-off-by: Fengguang Wu <[email protected]>
---
fs/proc/task_mmu.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
--- linux-2.6.23-rc2-mm2.orig/fs/proc/task_mmu.c
+++ linux-2.6.23-rc2-mm2/fs/proc/task_mmu.c
@@ -319,6 +319,7 @@ const struct file_operations proc_maps_o
struct mem_size_stats
{
unsigned long resident;
+ u64 pss; /* proportional set size: my share of rss */
unsigned long shared_clean;
unsigned long shared_dirty;
unsigned long private_clean;
@@ -341,6 +342,7 @@ static int smaps_pte_range(pmd_t *pmd, u
pte_t *pte, ptent;
spinlock_t *ptl;
struct page *page;
+ int mapcount;
pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
for (; addr != end; pte++, addr += PAGE_SIZE) {
@@ -357,16 +359,19 @@ static int smaps_pte_range(pmd_t *pmd, u
/* Accumulate the size in pages that have been accessed. */
if (pte_young(ptent) || PageReferenced(page))
mss->referenced += PAGE_SIZE;
- if (page_mapcount(page) >= 2) {
+ mapcount = page_mapcount(page);
+ if (mapcount >= 2) {
if (pte_dirty(ptent))
mss->shared_dirty += PAGE_SIZE;
else
mss->shared_clean += PAGE_SIZE;
+ mss->pss += (PAGE_SIZE << 12) / mapcount;
} else {
if (pte_dirty(ptent))
mss->private_dirty += PAGE_SIZE;
else
mss->private_clean += PAGE_SIZE;
+ mss->pss += (PAGE_SIZE << 12);
}
}
pte_unmap_unlock(pte - 1, ptl);
@@ -395,18 +400,20 @@ static int show_smap(struct seq_file *m,
seq_printf(m,
"Size: %8lu kB\n"
"Rss: %8lu kB\n"
+ "Pss: %8lu kB\n"
"Shared_Clean: %8lu kB\n"
"Shared_Dirty: %8lu kB\n"
"Private_Clean: %8lu kB\n"
"Private_Dirty: %8lu kB\n"
"Referenced: %8lu kB\n",
(vma->vm_end - vma->vm_start) >> 10,
- sarg.mss.resident >> 10,
+ sarg.mss.resident >> 10,
+ (unsigned long)(mss->pss >> 22),
sarg.mss.shared_clean >> 10,
sarg.mss.shared_dirty >> 10,
sarg.mss.private_clean >> 10,
sarg.mss.private_dirty >> 10,
- sarg.mss.referenced >> 10);
+ sarg.mss.referenced >> 10);
return ret;
}
-
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