Fengguang Wu wrote: > 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]>
I like the idea of moving towards PSS. I had sent some patches back in December last year http://marc.info/?l=linux-mm&m=116738715329816&w=4 > --- > 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) { This accounting is of-course racy. Mapcount can change any moment. > 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; > } > If we are reasonably sure that mapping will not change at the time of page_rmap_xxxxx() operations, we could handle shared accounting at those points and implement accurate shared accounting. -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
