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mm: smaps: split PSS into components

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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.

All the information is already present in /proc/pid/smaps, but much more
expensive to obtain because of the large size of that procfs entry.

This patch also removes a small code duplication in smaps_account, which
would have gotten worse otherwise.

Also updated Documentation/filesystems/proc.txt (the smaps section was a
bit stale, and I added a smaps_rollup section) and
Documentation/ABI/testing/procfs-smaps_rollup.

[semenzato@chromium.org: v5]
  Link: http://lkml.kernel.org/r/20190626234333.44608-1-semenzato@chromium.org
Link: http://lkml.kernel.org/r/20190626180429.174569-1-semenzato@chromium.org
Signed-off-by: Luigi Semenzato <semenzato@chromium.org>
Acked-by: Yu Zhao <yuzhao@chromium.org>
Cc: Sonny Rao <sonnyrao@chromium.org>
Cc: Yu Zhao <yuzhao@chromium.org>
Cc: Brian Geffon <bgeffon@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Luigi Semenzato
2019-07-11 21:00:10 -07:00
committed by Linus Torvalds
parent 1e426fe282
commit ee2ad71b07
3 changed files with 105 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files

92
fs/proc/task_mmu.c
View File

@@ -421,17 +421,53 @@ 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))
@@ -444,42 +480,25 @@ 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;
if (mapcount >= 2)
pss /= mapcount;
smaps_page_accumulate(mss, page, PAGE_SIZE, pss, dirty, locked,
mapcount < 2);
}
}
@@ -758,10 +777,23 @@ 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);
@@ -798,7 +830,7 @@ 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));
@@ -848,7 +880,7 @@ 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);