From: Luigi Semenzato <semenzato@xxxxxxxxxxxx> Subject: mm: smaps: split PSS into components 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@xxxxxxxxxxxx: v5] Link: http://lkml.kernel.org/r/20190626234333.44608-1-semenzato@xxxxxxxxxxxx Link: http://lkml.kernel.org/r/20190626180429.174569-1-semenzato@xxxxxxxxxxxx Signed-off-by: Luigi Semenzato <semenzato@xxxxxxxxxxxx> Acked-by: Yu Zhao <yuzhao@xxxxxxxxxxxx> Cc: Sonny Rao <sonnyrao@xxxxxxxxxxxx> Cc: Yu Zhao <yuzhao@xxxxxxxxxxxx> Cc: Brian Geffon <bgeffon@xxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- Documentation/ABI/testing/procfs-smaps_rollup | 14 ++ Documentation/filesystems/proc.txt | 41 +++++-- fs/proc/task_mmu.c | 92 ++++++++++------ 3 files changed, 105 insertions(+), 42 deletions(-) --- a/Documentation/ABI/testing/procfs-smaps_rollup~mm-smaps-split-pss-into-components +++ a/Documentation/ABI/testing/procfs-smaps_rollup @@ -3,18 +3,28 @@ Date: August 2017 Contact: Daniel Colascione <dancol@xxxxxxxxxx> Description: This file provides pre-summed memory information for a - process. The format is identical to /proc/pid/smaps, + process. The format is almost identical to /proc/pid/smaps, except instead of an entry for each VMA in a process, smaps_rollup has a single entry (tagged "[rollup]") for which each field is the sum of the corresponding fields from all the maps in /proc/pid/smaps. - For more details, see the procfs man page. + Additionally, the fields Pss_Anon, Pss_File and Pss_Shmem + are not present in /proc/pid/smaps. These fields represent + the sum of the Pss field of each type (anon, file, shmem). + For more details, see Documentation/filesystems/proc.txt + and the procfs man page. Typical output looks like this: 00100000-ff709000 ---p 00000000 00:00 0 [rollup] + Size: 1192 kB + KernelPageSize: 4 kB + MMUPageSize: 4 kB Rss: 884 kB Pss: 385 kB + Pss_Anon: 301 kB + Pss_File: 80 kB + Pss_Shmem: 4 kB Shared_Clean: 696 kB Shared_Dirty: 0 kB Private_Clean: 120 kB --- a/Documentation/filesystems/proc.txt~mm-smaps-split-pss-into-components +++ a/Documentation/filesystems/proc.txt @@ -154,9 +154,11 @@ Table 1-1: Process specific entries in / symbol the task is blocked in - or "0" if not blocked. pagemap Page table stack Report full stack trace, enable via CONFIG_STACKTRACE - smaps an extension based on maps, showing the memory consumption of + smaps An extension based on maps, showing the memory consumption of each mapping and flags associated with it - numa_maps an extension based on maps, showing the memory locality and + smaps_rollup Accumulated smaps stats for all mappings of the process. This + can be derived from smaps, but is faster and more convenient + numa_maps An extension based on maps, showing the memory locality and binding policy as well as mem usage (in pages) of each mapping. .............................................................................. @@ -366,7 +368,7 @@ Table 1-4: Contents of the stat files (a exit_code the thread's exit_code in the form reported by the waitpid system call .............................................................................. -The /proc/PID/maps file containing the currently mapped memory regions and +The /proc/PID/maps file contains the currently mapped memory regions and their access permissions. The format is: @@ -417,11 +419,14 @@ is not associated with a file: or if empty, the mapping is anonymous. The /proc/PID/smaps is an extension based on maps, showing the memory -consumption for each of the process's mappings. For each of mappings there -is a series of lines such as the following: +consumption for each of the process's mappings. For each mapping (aka Virtual +Memory Area, or VMA) there is a series of lines such as the following: 08048000-080bc000 r-xp 00000000 03:02 13130 /bin/bash + Size: 1084 kB +KernelPageSize: 4 kB +MMUPageSize: 4 kB Rss: 892 kB Pss: 374 kB Shared_Clean: 892 kB @@ -443,11 +448,14 @@ Locked: 0 kB THPeligible: 0 VmFlags: rd ex mr mw me dw -the first of these lines shows the same information as is displayed for the -mapping in /proc/PID/maps. The remaining lines show the size of the mapping -(size), the amount of the mapping that is currently resident in RAM (RSS), the -process' proportional share of this mapping (PSS), the number of clean and -dirty private pages in the mapping. +The first of these lines shows the same information as is displayed for the +mapping in /proc/PID/maps. Following lines show the size of the mapping +(size); the size of each page allocated when backing a VMA (KernelPageSize), +which is usually the same as the size in the page table entries; the page size +used by the MMU when backing a VMA (in most cases, the same as KernelPageSize); +the amount of the mapping that is currently resident in RAM (RSS); the +process' proportional share of this mapping (PSS); and the number of clean and +dirty shared and private pages in the mapping. 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. @@ -532,6 +540,19 @@ guarantees: 2) If there is something at a given vaddr during the entirety of the life of the smaps/maps walk, there will be some output for it. +The /proc/PID/smaps_rollup file includes the same fields as /proc/PID/smaps, +but their values are the sums of the corresponding values for all mappings of +the process. Additionally, it contains these fields: + +Pss_Anon +Pss_File +Pss_Shmem + +They represent the proportional shares of anonymous, file, and shmem pages, as +described for smaps above. These fields are omitted in smaps since each +mapping identifies the type (anon, file, or shmem) of all pages it contains. +Thus all information in smaps_rollup can be derived from smaps, but at a +significantly higher cost. The /proc/PID/clear_refs is used to reset the PG_Referenced and ACCESSED/YOUNG bits on both physical and virtual pages associated with a process, and the --- a/fs/proc/task_mmu.c~mm-smaps-split-pss-into-components +++ a/fs/proc/task_mmu.c @@ -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_siz 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_ 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, 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_ 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); _
