Re: [PATCH v5 00/12] MADV_FREE support

Hello Michael,

On Thu, Jan 28, 2016 at 08:16:25AM +0100, Michael Kerrisk (man-pages) wrote:

Hello Minchan,

On 11/30/2015 07:39 AM, Minchan Kim wrote:

quoted

In v4, Andrew wanted to settle in old basic MADV_FREE and introduces
new stuffs(ie, lazyfree LRU, swapless support and lazyfreeness) later
so this version doesn't include them.

I have been tested it on mmotm-2015-11-25-17-08 with additional
patch[1] from Kirill to prevent BUG_ON which he didn't send to
linux-mm yet as formal patch. With it, I couldn't find any
problem so far.

Note that this version is based on THP refcount redesign so
I needed some modification on MADV_FREE because split_huge_pmd
doesn't split a THP page any more and pmd_trans_huge(pmd) is not
enough to guarantee the page is not THP page.
As well, for MAVD_FREE lazy-split, THP split should respect
pmd's dirtiness rather than marking ptes of all subpages dirty
unconditionally. Please, review last patch in this patchset.

Now that MADV_FREE has been merged, would you be willing to write
patch to the madvise(2) man page that describes the semantics, 
noes limitations and restrictions, and (ideally) has some sentences
describing use cases?

I will try next week.
Thanks for the heads up.

Thanks,

Michael

quoted

	mm: don't split THP page when syscall is called

[1] https://lkml.org/lkml/2015/11/17/134

git: git://git.kernel.org/pub/scm/linux/kernel/git/minchan/linux.git
branch: mm/madv_free-v4.4-rc2-mmotm-2015-11-25-17-08-v5r2

In this stage, I don't think we need to write man page.
It could be done after solid policy and implementation.

 * Change from v4
   * drop lazyfree LRU
   * drop swapless support
   * drop lazyfreeness
   * rebase on recent mmotom with THP refcount redesign

 * Change from v3
   * some bug fix
   * code refactoring
   * lazyfree reclaim logic change
   * reordering patch

 * Change from v2
   * vm_lazyfreeness tuning knob
   * add new LRU list - Johannes, Shaohua
   * support swapless - Johannes

 * Change from v1
   * Don't do unnecessary TLB flush - Shaohua
   * Added Acked-by - Hugh, Michal
   * Merge deactivate_page and deactivate_file_page
   * Add pmd_dirty/pmd_mkclean patches for several arches
   * Add lazy THP split patch
   * Drop zhangyanfei-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org - Delivery Failure

Chen Gang (1):
  arch: uapi: asm: mman.h: Let MADV_FREE have same value for all
    architectures

Minchan Kim (11):
  mm: support madvise(MADV_FREE)
  mm: define MADV_FREE for some arches
  mm: free swp_entry in madvise_free
  mm: move lazily freed pages to inactive list
  mm: mark stable page dirty in KSM
  x86: add pmd_[dirty|mkclean] for THP
  sparc: add pmd_[dirty|mkclean] for THP
  powerpc: add pmd_[dirty|mkclean] for THP
  arm: add pmd_mkclean for THP
  arm64: add pmd_mkclean for THP
  mm: don't split THP page when syscall is called

 arch/alpha/include/uapi/asm/mman.h       |   2 +
 arch/arm/include/asm/pgtable-3level.h    |   1 +
 arch/arm64/include/asm/pgtable.h         |   1 +
 arch/mips/include/uapi/asm/mman.h        |   2 +
 arch/parisc/include/uapi/asm/mman.h      |   2 +
 arch/powerpc/include/asm/pgtable-ppc64.h |   2 +
 arch/sparc/include/asm/pgtable_64.h      |   9 ++
 arch/x86/include/asm/pgtable.h           |   5 +
 arch/xtensa/include/uapi/asm/mman.h      |   2 +
 include/linux/huge_mm.h                  |   3 +
 include/linux/rmap.h                     |   1 +
 include/linux/swap.h                     |   1 +
 include/linux/vm_event_item.h            |   1 +
 include/uapi/asm-generic/mman-common.h   |   1 +
 mm/huge_memory.c                         |  87 +++++++++++++-
 mm/ksm.c                                 |   6 +
 mm/madvise.c                             | 199 +++++++++++++++++++++++++++++++
 mm/rmap.c                                |   8 ++
 mm/swap.c                                |  44 +++++++
 mm/swap_state.c                          |   5 +-
 mm/vmscan.c                              |  10 +-
 mm/vmstat.c                              |   1 +
 22 files changed, 383 insertions(+), 10 deletions(-)

-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/