On 12/04/2024 08:37, Barry Song wrote: > From: Barry Song <v-songbaohua@xxxxxxxx> > > This patch includes documentation for mTHP counters and an ABI file > for sys-kernel-mm-transparent-hugepage, which appears to have been > missing for some time. > > Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx> > Cc: Chris Li <chrisl@xxxxxxxxxx> > Cc: David Hildenbrand <david@xxxxxxxxxx> > Cc: Domenico Cerasuolo <cerasuolodomenico@xxxxxxxxx> > Cc: Kairui Song <kasong@xxxxxxxxxxx> > Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> > Cc: Peter Xu <peterx@xxxxxxxxxx> > Cc: Ryan Roberts <ryan.roberts@xxxxxxx> > Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx> > Cc: Yosry Ahmed <yosryahmed@xxxxxxxxxx> > Cc: Yu Zhao <yuzhao@xxxxxxxxxx> > Cc: Jonathan Corbet <corbet@xxxxxxx> A few nits, but regardless: Reviewed-by: Ryan Roberts <ryan.roberts@xxxxxxx> > --- > .../sys-kernel-mm-transparent-hugepage | 17 +++++++++++ > Documentation/admin-guide/mm/transhuge.rst | 28 +++++++++++++++++++ > 2 files changed, 45 insertions(+) > create mode 100644 Documentation/ABI/testing/sys-kernel-mm-transparent-hugepage > > diff --git a/Documentation/ABI/testing/sys-kernel-mm-transparent-hugepage b/Documentation/ABI/testing/sys-kernel-mm-transparent-hugepage > new file mode 100644 > index 000000000000..80dde0fd576c > --- /dev/null > +++ b/Documentation/ABI/testing/sys-kernel-mm-transparent-hugepage > @@ -0,0 +1,17 @@ > +What: /sys/kernel/mm/hugepages/ Err, transparent_hugepage, right? copy/paste error? > +Date: April 2024 > +Contact: Barry Song <baohua@xxxxxxxxxx> Looks like a bunch of mm sysfs interfaces use: Contact: Linux memory management mailing list <linux-mm@xxxxxxxxx> I'll leave that up to you! > +Description: > + /sys/kernel/mm/transparent_hugepage/ contains a number of files and > + subdirectories, > + - defrag > + - enabled > + - hpage_pmd_size > + - khugepaged > + - shmem_enabled > + - use_zero_page > + - subdirectories of the form hugepages-<size>kB, where <size> > + is the page size of the hugepages supported by the kernel/CPU > + combination. > + > + See Documentation/admin-guide/mm/transhuge.rst for details.> diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst > index 04eb45a2f940..f436ff982f22 100644 > --- a/Documentation/admin-guide/mm/transhuge.rst > +++ b/Documentation/admin-guide/mm/transhuge.rst > @@ -447,6 +447,34 @@ thp_swpout_fallback > Usually because failed to allocate some continuous swap space > for the huge page. > > +In /sys/kernel/mm/transparent_hugepage/hugepages-<size>kB/stats, There are > +also individual counters for each huge page size, which can be utilized to > +monitor the system's effectiveness in providing huge pages for usage. Each > +counter has its own corresponding file. > + > +anon_fault_alloc > + is incremented every time a huge page is successfully > + allocated and charged to handle a page fault. > + > +anon_fault_fallback > + is incremented if a page fault fails to allocate or charge > + a huge page and instead falls back to using huge pages with > + lower orders or small pages. > + > +anon_fault_fallback_charge > + is incremented if a page fault fails to charge a huge page and > + instead falls back to using huge pages with lower orders or > + small pages even though the allocation was successful. > + > +anon_swpout > + is incremented every time a huge page is swapout in one nit: swapout -> "swapped out"? Although I see this is just a copy/paste of the description of the existing counter... > + piece without splitting. > + > +anon_swpout_fallback > + is incremented if a huge page has to be split before swapout. > + Usually because failed to allocate some continuous swap space > + for the huge page. > + > As the system ages, allocating huge pages may be expensive as the > system uses memory compaction to copy data around memory to free a > huge page for use. There are some counters in ``/proc/vmstat`` to help
