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Message-Id: <2.430487409@selenic.com> Date: Fri, 26 Oct 2007 11:36:27 -0500 From: Matt Mackall <mpm@...enic.com> To: Andrew Morton <akpm@...ux-foundation.org>, linux-kernel@...r.kernel.org Cc: Dave Hansen <haveblue@...ibm.com>, Rusty Russell <rusty@...tcorp.com.au>, Jeremy Fitzhardinge <jeremy@...p.org>, David Rientjes <rientjes@...gle.com>, Fengguang Wu <wfg@...l.ustc.edu.cn> Subject: [PATCH 1/12] maps4: add proportional set size accounting in smaps From: Fengguang Wu <wfg@...l.ustc.edu.cn> 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. They are comprehensive tools. But for PSS, let's do it in the simple way. Cc: John Berthels <jjberthels@...il.com> Cc: Bernardo Innocenti <bernie@...ewiz.org> Cc: Padraig Brady <P@...igBrady.com> Cc: Denys Vlasenko <vda.linux@...glemail.com> Cc: Balbir Singh <balbir@...ux.vnet.ibm.com> Signed-off-by: Matt Mackall <mpm@...enic.com> Signed-off-by: Fengguang Wu <wfg@...l.ustc.edu.cn> Cc: Hugh Dickins <hugh@...itas.com> --- fs/proc/task_mmu.c | 29 ++++++++++++++++++++++++++++- 1 files changed, 28 insertions(+), 1 deletion(-) Index: l/fs/proc/task_mmu.c =================================================================== --- l.orig/fs/proc/task_mmu.c 2007-10-16 21:13:47.000000000 -0500 +++ l/fs/proc/task_mmu.c 2007-10-22 15:53:12.000000000 -0500 @@ -114,6 +114,25 @@ static void pad_len_spaces(struct seq_fi seq_printf(m, "%*c", len, ' '); } +/* + * Proportional Set Size(PSS): my share of RSS. + * + * 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. + * + * To keep (accumulated) division errors low, we adopt a 64bit + * fixed-point pss counter to minimize division errors. So (pss >> + * PSS_SHIFT) would be the real byte count. + * + * A shift of 12 before division means (assuming 4K page size): + * - 1M 3-user-pages add up to 8KB errors; + * - supports mapcount up to 2^24, or 16M; + * - supports PSS up to 2^52 bytes, or 4PB. + */ +#define PSS_SHIFT 12 + struct mem_size_stats { unsigned long resident; @@ -122,6 +141,7 @@ struct mem_size_stats unsigned long private_clean; unsigned long private_dirty; unsigned long referenced; + u64 pss; }; struct pmd_walker { @@ -195,6 +215,7 @@ static int show_map_internal(struct seq_ 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" @@ -202,6 +223,7 @@ static int show_map_internal(struct seq_ "Referenced: %8lu kB\n", (vma->vm_end - vma->vm_start) >> 10, mss->resident >> 10, + (unsigned long)(mss.pss >> (10 + PSS_SHIFT)), mss->shared_clean >> 10, mss->shared_dirty >> 10, mss->private_clean >> 10, @@ -226,6 +248,7 @@ static void smaps_pte_range(struct vm_ar 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) { @@ -242,16 +265,19 @@ static void smaps_pte_range(struct vm_ar /* 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 << PSS_SHIFT) / mapcount; } else { if (pte_dirty(ptent)) mss->private_dirty += PAGE_SIZE; else mss->private_clean += PAGE_SIZE; + mss->pss += (PAGE_SIZE << PSS_SHIFT); } } pte_unmap_unlock(pte - 1, ptl); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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