| From: Vincent Whitchurch <vincent.whitchurch@axis.com> |
| Subject: mm/smaps: add Pss_Dirty |
| Date: Mon, 20 Jun 2022 10:12:50 +0200 |
| |
| Pss is the sum of the sizes of clean and dirty private pages, and the |
| proportional sizes of clean and dirty shared pages: |
| |
| Private = Private_Dirty + Private_Clean |
| Shared_Proportional = Shared_Dirty_Proportional + Shared_Clean_Proportional |
| Pss = Private + Shared_Proportional |
| |
| The Shared*Proportional fields are not present in smaps, so it is not |
| always possible to determine how much of the Pss is from dirty pages and |
| how much is from clean pages. This information can be useful for |
| measuring memory usage for the purpose of optimisation, since clean pages |
| can usually be discarded by the kernel immediately while dirty pages |
| cannot. |
| |
| The smaps routines in the kernel already have access to this data, so add |
| a Pss_Dirty to show it to userspace. Pss_Clean is not added since it can |
| be calculated from Pss and Pss_Dirty. |
| |
| Link: https://lkml.kernel.org/r/20220620081251.2928103-1-vincent.whitchurch@axis.com |
| Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com> |
| Cc: Jonathan Corbet <corbet@lwn.net> |
| Cc: Alexey Dobriyan <adobriyan@gmail.com> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| --- |
| |
| Documentation/ABI/testing/procfs-smaps_rollup | 1 + |
| Documentation/filesystems/proc.rst | 5 ++++- |
| fs/proc/task_mmu.c | 3 +++ |
| 3 files changed, 8 insertions(+), 1 deletion(-) |
| |
| --- a/Documentation/ABI/testing/procfs-smaps_rollup~mm-smaps-add-pss_dirty |
| +++ a/Documentation/ABI/testing/procfs-smaps_rollup |
| @@ -22,6 +22,7 @@ Description: |
| MMUPageSize: 4 kB |
| Rss: 884 kB |
| Pss: 385 kB |
| + Pss_Dirty: 68 kB |
| Pss_Anon: 301 kB |
| Pss_File: 80 kB |
| Pss_Shmem: 4 kB |
| --- a/Documentation/filesystems/proc.rst~mm-smaps-add-pss_dirty |
| +++ a/Documentation/filesystems/proc.rst |
| @@ -448,6 +448,7 @@ Memory Area, or VMA) there is a series o |
| MMUPageSize: 4 kB |
| Rss: 892 kB |
| Pss: 374 kB |
| + Pss_Dirty: 0 kB |
| Shared_Clean: 892 kB |
| Shared_Dirty: 0 kB |
| Private_Clean: 0 kB |
| @@ -479,7 +480,9 @@ dirty shared and private pages in the ma |
| 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. |
| +process, its PSS will be 1500. "Pss_Dirty" is the portion of PSS which |
| +consists of dirty pages. ("Pss_Clean" is not included, but it can be |
| +calculated by subtracting "Pss_Dirty" from "Pss".) |
| |
| Note that even a page which is part of a MAP_SHARED mapping, but has only |
| a single pte mapped, i.e. is currently used by only one process, is accounted |
| --- a/fs/proc/task_mmu.c~mm-smaps-add-pss_dirty |
| +++ a/fs/proc/task_mmu.c |
| @@ -406,6 +406,7 @@ struct mem_size_stats { |
| u64 pss_anon; |
| u64 pss_file; |
| u64 pss_shmem; |
| + u64 pss_dirty; |
| u64 pss_locked; |
| u64 swap_pss; |
| }; |
| @@ -427,6 +428,7 @@ static void smaps_page_accumulate(struct |
| mss->pss_locked += pss; |
| |
| if (dirty || PageDirty(page)) { |
| + mss->pss_dirty += pss; |
| if (private) |
| mss->private_dirty += size; |
| else |
| @@ -808,6 +810,7 @@ static void __show_smap(struct seq_file |
| { |
| SEQ_PUT_DEC("Rss: ", mss->resident); |
| SEQ_PUT_DEC(" kB\nPss: ", mss->pss >> PSS_SHIFT); |
| + SEQ_PUT_DEC(" kB\nPss_Dirty: ", mss->pss_dirty >> PSS_SHIFT); |
| if (rollup_mode) { |
| /* |
| * These are meaningful only for smaps_rollup, otherwise two of |
| _ |
