Re: [PATCHv2, RFC 00/30] Transparent huge page cache

[Simon Jeons <simon.jeons@gmail.com>]

Hi Kirill,
On 03/15/2013 01:50 AM, Kirill A. Shutemov wrote:
> From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
>
> Here's the second version of the patchset.
>
> The intend of the work is get code ready to enable transparent huge page
> cache for the most simple fs -- ramfs.
>
> We have read()/write()/mmap() functionality now. Still plenty work ahead.

One offline question.

Why set PG_mlocked to page_tail which be splited in function 
__split_huge_page_refcount?

>
> Any feedback is welcome.
>
> Changes since v1:
>   - mmap();
>   - fix add_to_page_cache_locked() and delete_from_page_cache();
>   - introduce mapping_can_have_hugepages();
>   - call split_huge_page() only for head page in filemap_fault();
>   - wait_split_huge_page(): serialize over i_mmap_mutex too;
>   - lru_add_page_tail: avoid PageUnevictable on active/inactive lru lists;
>   - fix off-by-one in zero_huge_user_segment();
>   - THP_WRITE_ALLOC/THP_WRITE_FAILED counters;
>
> TODO:
>   - memcg accounting has not yet evaluated;
>   - collapse;
>   - migration (?);
>   - stats, knobs, etc.;
>   - tmpfs/shmem enabling;
>
>
> Kirill A. Shutemov (30):
>    block: implement add_bdi_stat()
>    mm: implement zero_huge_user_segment and friends
>    mm: drop actor argument of do_generic_file_read()
>    radix-tree: implement preload for multiple contiguous elements
>    thp, mm: avoid PageUnevictable on active/inactive lru lists
>    thp, mm: basic defines for transparent huge page cache
>    thp, mm: introduce mapping_can_have_hugepages() predicate
>    thp, mm: rewrite add_to_page_cache_locked() to support huge pages
>    thp, mm: rewrite delete_from_page_cache() to support huge pages
>    thp, mm: locking tail page is a bug
>    thp, mm: handle tail pages in page_cache_get_speculative()
>    thp, mm: add event counters for huge page alloc on write to a file
>    thp, mm: implement grab_cache_huge_page_write_begin()
>    thp, mm: naive support of thp in generic read/write routines
>    thp, libfs: initial support of thp in
>      simple_read/write_begin/write_end
>    thp: handle file pages in split_huge_page()
>    thp: wait_split_huge_page(): serialize over i_mmap_mutex too
>    thp, mm: truncate support for transparent huge page cache
>    thp, mm: split huge page on mmap file page
>    ramfs: enable transparent huge page cache
>    x86-64, mm: proper alignment mappings with hugepages
>    mm: add huge_fault() callback to vm_operations_struct
>    thp: prepare zap_huge_pmd() to uncharge file pages
>    thp: move maybe_pmd_mkwrite() out of mk_huge_pmd()
>    thp, mm: basic huge_fault implementation for generic_file_vm_ops
>    thp: extract fallback path from do_huge_pmd_anonymous_page() to a
>      function
>    thp: initial implementation of do_huge_linear_fault()
>    thp: handle write-protect exception to file-backed huge pages
>    thp: call __vma_adjust_trans_huge() for file-backed VMA
>    thp: map file-backed huge pages on fault
>
>   arch/x86/kernel/sys_x86_64.c  |   13 +-
>   fs/libfs.c                    |   50 ++++-
>   fs/ramfs/inode.c              |    6 +-
>   include/linux/backing-dev.h   |   10 +
>   include/linux/huge_mm.h       |   36 +++-
>   include/linux/mm.h            |   16 ++
>   include/linux/pagemap.h       |   24 ++-
>   include/linux/radix-tree.h    |    3 +
>   include/linux/vm_event_item.h |    2 +
>   lib/radix-tree.c              |   32 ++-
>   mm/filemap.c                  |  283 +++++++++++++++++++++----
>   mm/huge_memory.c              |  462 ++++++++++++++++++++++++++++++++++-------
>   mm/memory.c                   |   31 ++-
>   mm/swap.c                     |    3 +-
>   mm/truncate.c                 |   12 ++
>   mm/vmstat.c                   |    2 +
>   16 files changed, 842 insertions(+), 143 deletions(-)
>

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