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On Thu 30-05-19 17:26:33, semenzato@xxxxxxxxxxxx wrote:
> From: Luigi Semenzato <semenzato@xxxxxxxxxxxx>
>
> Report separate components (anon, file, and shmem)
> for PSS in smaps_rollup.
>
> This helps understand and tune the memory manager behavior
> in consumer devices, particularly mobile devices. Many of
> them (e.g. chromebooks and Android-based devices) use zram
> for anon memory, and perform disk reads for discarded file
> pages. The difference in latency is large (e.g. reading
> a single page from SSD is 30 times slower than decompressing
> a zram page on one popular device), thus it is useful to know
> how much of the PSS is anon vs. file.
>
> This patch also removes a small code duplication in smaps_account,
> which would have gotten worse otherwise.
>
> Acked-by: Yu Zhao <yuzhao@xxxxxxxxxxxx>
> Signed-off-by: Luigi Semenzato <semenzato@xxxxxxxxxxxx>
> ---
> fs/proc/task_mmu.c | 91 +++++++++++++++++++++++++++++++---------------
> 1 file changed, 61 insertions(+), 30 deletions(-)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 01d4eb0e6bd1..ed3b952f0d30 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -417,17 +417,53 @@ struct mem_size_stats {
> unsigned long shared_hugetlb;
> unsigned long private_hugetlb;
> u64 pss;
> + u64 pss_anon;
> + u64 pss_file;
> + u64 pss_shmem;
> u64 pss_locked;
> u64 swap_pss;
> bool check_shmem_swap;
> };
>
> +static void smaps_page_accumulate(struct mem_size_stats *mss,
> + struct page *page, unsigned long size, unsigned long pss,
> + bool dirty, bool locked, bool private)
> +{
> + mss->pss += pss;
> +
> + if (PageAnon(page))
> + mss->pss_anon += pss;
> + else if (PageSwapBacked(page))
> + mss->pss_shmem += pss;
> + else
> + mss->pss_file += pss;
> +
> + if (locked)
> + mss->pss_locked += pss;
> +
> + if (dirty || PageDirty(page)) {
> + if (private)
> + mss->private_dirty += size;
> + else
> + mss->shared_dirty += size;
> + } else {
> + if (private)
> + mss->private_clean += size;
> + else
> + mss->shared_clean += size;
> + }
> +}
> +
> static void smaps_account(struct mem_size_stats *mss, struct page *page,
> bool compound, bool young, bool dirty, bool locked)
> {
> int i, nr = compound ? 1 << compound_order(page) : 1;
> unsigned long size = nr * PAGE_SIZE;
>
> + /*
> + * First accumulate quantities that depend only on |size| and the type
> + * of the compound page.
> + */
> if (PageAnon(page)) {
> mss->anonymous += size;
> if (!PageSwapBacked(page) && !dirty && !PageDirty(page))
> @@ -440,42 +476,24 @@ static void smaps_account(struct mem_size_stats *mss, struct page *page,
> mss->referenced += size;
>
> /*
> + * Then accumulate quantities that may depend on sharing, or that may
> + * differ page-by-page.
> + *
> * page_count(page) == 1 guarantees the page is mapped exactly once.
> * If any subpage of the compound page mapped with PTE it would elevate
> * page_count().
> */
> if (page_count(page) == 1) {
> - if (dirty || PageDirty(page))
> - mss->private_dirty += size;
> - else
> - mss->private_clean += size;
> - mss->pss += (u64)size << PSS_SHIFT;
> - if (locked)
> - mss->pss_locked += (u64)size << PSS_SHIFT;
> + smaps_page_accumulate(mss, page, size, size << PSS_SHIFT, dirty,
> + locked, true);
> return;
> }
> -
> for (i = 0; i < nr; i++, page++) {
> int mapcount = page_mapcount(page);
> - unsigned long pss = (PAGE_SIZE << PSS_SHIFT);
> -
> - if (mapcount >= 2) {
> - if (dirty || PageDirty(page))
> - mss->shared_dirty += PAGE_SIZE;
> - else
> - mss->shared_clean += PAGE_SIZE;
> - mss->pss += pss / mapcount;
> - if (locked)
> - mss->pss_locked += pss / mapcount;
> - } else {
> - if (dirty || PageDirty(page))
> - mss->private_dirty += PAGE_SIZE;
> - else
> - mss->private_clean += PAGE_SIZE;
> - mss->pss += pss;
> - if (locked)
> - mss->pss_locked += pss;
> - }
> + unsigned long pss = PAGE_SIZE << PSS_SHIFT;
> +
> + smaps_page_accumulate(mss, page, PAGE_SIZE, pss / mapcount,
> + dirty, locked, mapcount < 2);
> }
> }
>
> @@ -754,10 +772,23 @@ static void smap_gather_stats(struct vm_area_struct *vma,
> seq_put_decimal_ull_width(m, str, (val) >> 10, 8)
>
> /* Show the contents common for smaps and smaps_rollup */
> -static void __show_smap(struct seq_file *m, const struct mem_size_stats *mss)
> +static void __show_smap(struct seq_file *m, const struct mem_size_stats *mss,
> + bool rollup_mode)
> {
> SEQ_PUT_DEC("Rss: ", mss->resident);
> SEQ_PUT_DEC(" kB\nPss: ", mss->pss >> PSS_SHIFT);
> + if (rollup_mode) {
> + /*
> + * These are meaningful only for smaps_rollup, otherwise two of
> + * them are zero, and the other one is the same as Pss.
> + */
> + SEQ_PUT_DEC(" kB\nPss_Anon: ",
> + mss->pss_anon >> PSS_SHIFT);
> + SEQ_PUT_DEC(" kB\nPss_File: ",
> + mss->pss_file >> PSS_SHIFT);
> + SEQ_PUT_DEC(" kB\nPss_Shmem: ",
> + mss->pss_shmem >> PSS_SHIFT);
> + }
> SEQ_PUT_DEC(" kB\nShared_Clean: ", mss->shared_clean);
> SEQ_PUT_DEC(" kB\nShared_Dirty: ", mss->shared_dirty);
> SEQ_PUT_DEC(" kB\nPrivate_Clean: ", mss->private_clean);
> @@ -794,7 +825,7 @@ static int show_smap(struct seq_file *m, void *v)
> SEQ_PUT_DEC(" kB\nMMUPageSize: ", vma_mmu_pagesize(vma));
> seq_puts(m, " kB\n");
>
> - __show_smap(m, &mss);
> + __show_smap(m, &mss, false);
>
> seq_printf(m, "THPeligible: %d\n", transparent_hugepage_enabled(vma));
>
> @@ -841,7 +872,7 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
> seq_pad(m, ' ');
> seq_puts(m, "[rollup]\n");
>
> - __show_smap(m, &mss);
> + __show_smap(m, &mss, true);
>
> release_task_mempolicy(priv);
> up_read(&mm->mmap_sem);
> --
> 2.22.0.rc1.257.g3120a18244-goog
--
Michal Hocko
SUSE Labs
