David Hildenbrand <david@xxxxxxxxxx> writes: > Sorry for the late reply, Gmail once again decided to classify your mails as > spam (for whatever reason). > > On 11.08.23 18:28, Stefan Roesch wrote: >> With madvise and prctl KSM can be enabled for different VMA's. Once it >> is enabled we can query how effective KSM is overall. However we cannot >> easily query if an individual VMA benefits from KSM. >> This commit adds a KSM section to the /prod/<pid>/smaps file. It reports >> how many of the pages are KSM pages. >> Here is a typical output: >> 7f420a000000-7f421a000000 rw-p 00000000 00:00 0 >> Size: 262144 kB >> KernelPageSize: 4 kB >> MMUPageSize: 4 kB >> Rss: 51212 kB >> Pss: 8276 kB >> Shared_Clean: 172 kB >> Shared_Dirty: 42996 kB >> Private_Clean: 196 kB >> Private_Dirty: 7848 kB >> Referenced: 15388 kB >> Anonymous: 51212 kB >> KSM: 41376 kB >> LazyFree: 0 kB >> AnonHugePages: 0 kB >> ShmemPmdMapped: 0 kB >> FilePmdMapped: 0 kB >> Shared_Hugetlb: 0 kB >> Private_Hugetlb: 0 kB >> Swap: 202016 kB >> SwapPss: 3882 kB >> Locked: 0 kB >> THPeligible: 0 >> ProtectionKey: 0 >> ksm_state: 0 >> ksm_skip_base: 0 >> ksm_skip_count: 0 >> VmFlags: rd wr mr mw me nr mg anon >> This information also helps with the following workflow: >> - First enable KSM for all the VMA's of a process with prctl. >> - Then analyze with the above smaps report which VMA's benefit the most >> - Change the application (if possible) to add the corresponding madvise >> calls for the VMA's that benefit the most >> Signed-off-by: Stefan Roesch <shr@xxxxxxxxxxxx> >> --- >> Documentation/filesystems/proc.rst | 3 +++ >> fs/proc/task_mmu.c | 5 +++++ >> 2 files changed, 8 insertions(+) >> diff --git a/Documentation/filesystems/proc.rst >> b/Documentation/filesystems/proc.rst >> index 7897a7dafcbc..4ef3c0bbf16a 100644 >> --- a/Documentation/filesystems/proc.rst >> +++ b/Documentation/filesystems/proc.rst >> @@ -461,6 +461,7 @@ Memory Area, or VMA) there is a series of lines such as the following:: >> Private_Dirty: 0 kB >> Referenced: 892 kB >> Anonymous: 0 kB >> + KSM: 0 kB >> LazyFree: 0 kB >> AnonHugePages: 0 kB >> ShmemPmdMapped: 0 kB >> @@ -501,6 +502,8 @@ accessed. >> a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE >> and a page is modified, the file page is replaced by a private anonymous copy. >> +"KSM" shows the amount of anonymous memory that has been de-duplicated. > > > How do we want to treat memory that has been deduplicated into the shared > zeropage? > > It would also match this description. > > See in mm-stable: > > commit 30ff6ed9a65c7e73545319fc15f7bcf9c52457eb > Author: xu xin <xu.xin16@xxxxxxxxxx> > Date: Tue Jun 13 11:09:28 2023 +0800 > > ksm: support unsharing KSM-placed zero pages > > Patch series "ksm: support tracking KSM-placed zero-pages", v10. I see two approaches how to deal with zero page: - If zero page is not enabled, it works as is - If enabled - Document that zero page is accounted for the current vma or - Pass in the pte from smaps_pte_entry() to smaps_account() so we can determine if this is a zero page. I'm not sure what to do about smaps_pmd_entry in that case. We probably don't care about compund pages.