Re: [PATCH] Export amount of anonymous memory in a mapping via smaps

Hugh Dickins
2010-09-16T16:40:25Z

On Thu, 16 Sep 2010, Nikanth Karthikesan wrote:

> Export the number of anonymous pages in a mapping via smaps.
>
> Even the private pages in a mapping backed by a file, would be marked as
> anonymous, when they are modified. Export this information to user-space via
> smaps.
>
> Signed-off-by: Nikanth Karthikesan <knikanth@suse.de>

Acked-by: Hugh Dickins <hughd@google.com>

but I'd prefer if we added a little more justification, such as:

Exporting this count will help gdb to make a better decision on which
areas need to be dumped in its coredump; and should be useful to others
studying the memory usage of a process.

>
> ---
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 439fc1f..3c18fc8 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -326,6 +326,7 @@ struct mem_size_stats {
> unsigned long private_clean;
> unsigned long private_dirty;
> unsigned long referenced;
> + unsigned long anonymous;
> unsigned long swap;
> u64 pss;
> };
> @@ -356,6 +357,9 @@ static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
> if (!page)
> continue;
>
> + if (PageAnon(page))
> + mss->anonymous += PAGE_SIZE;
> +
> mss->resident += PAGE_SIZE;
> /* Accumulate the size in pages that have been accessed. */
> if (pte_young(ptent) || PageReferenced(page))
> @@ -409,6 +413,7 @@ static int show_smap(struct seq_file *m, void *v)
> "Private_Clean: %8lu kB\n"
> "Private_Dirty: %8lu kB\n"
> "Referenced: %8lu kB\n"
> + "Anonymous: %8lu kB\n"
> "Swap: %8lu kB\n"
> "KernelPageSize: %8lu kB\n"
> "MMUPageSize: %8lu kB\n",
> @@ -420,6 +425,7 @@ static int show_smap(struct seq_file *m, void *v)
> mss.private_clean >> 10,
> mss.private_dirty >> 10,
> mss.referenced >> 10,
> + mss.anonymous >> 10,
> mss.swap >> 10,
> vma_kernel_pagesize(vma) >> 10,
> vma_mmu_pagesize(vma) >> 10);
>
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