[PATCH *] rmap VM 12d

[PATCH *] rmap VM 12d

[Rik van Riel]

The fourth maintenance release of the 12th version of the reverse
mapping based VM is now available.
This is an attempt at making a more robust and flexible VM
subsystem, while cleaning up a lot of code at the same time.
The patch is available from:

           http://surriel.com/patches/2.4/2.4.17-rmap-12d
and        http://linuxvm.bkbits.net/


My big TODO items for a next release are:
  - auto-tuning readahead, readahead per VMA
  - fix starvation issue in get_request_wait()

rmap 12d:
  - fix compiler warning in rmap.c                        (Roger Larsson)
  - read latency improvement   (read-latency2)            (Andrew Morton)
rmap 12c:
  - fix small balancing bug in page_launder_zone          (Nick Piggin)
  - wakeup_kswapd / wakeup_memwaiters code fix            (Arjan van de Ven)
  - improve RSS limit enforcement                         (me)
rmap 12b:
  - highmem emulation (for debugging purposes)            (Andrea Arcangeli)
  - ulimit RSS enforcement when memory gets tight         (me)
  - sparc64 page->virtual quickfix                        (Greg Procunier)
rmap 12a:
  - fix the compile warning in buffer.c                   (me)
  - fix divide-by-zero on highmem initialisation  DOH!    (me)
  - remove the pgd quicklist (suspicious ...)             (DaveM, me)
rmap 12:
  - keep some extra free memory on large machines         (Arjan van de Ven, me)
  - higher-order allocation bugfix                        (Adrian Drzewiecki)
  - nr_free_buffer_pages() returns inactive + free mem    (me)
  - pages from unused objects directly to inactive_clean  (me)
  - use fast pte quicklists on non-pae machines           (Andrea Arcangeli)
  - remove sleep_on from wakeup_kswapd                    (Arjan van de Ven)
  - page waitqueue cleanup                                (Christoph Hellwig)
rmap 11c:
  - oom_kill race locking fix                             (Andres Salomon)
  - elevator improvement                                  (Andrew Morton)
  - dirty buffer writeout speedup (hopefully ;))          (me)
  - small documentation updates                           (me)
  - page_launder() never does synchronous IO, kswapd
    and the processes calling it sleep on higher level    (me)
  - deadlock fix in touch_page()                          (me)
rmap 11b:
  - added low latency reschedule points in vmscan.c       (me)
  - make i810_dma.c include mm_inline.h too               (William Lee Irwin)
  - wake up kswapd sleeper tasks on OOM kill so the
    killed task can continue on its way out               (me)
  - tune page allocation sleep point a little             (me)
rmap 11a:
  - don't let refill_inactive() progress count for OOM    (me)
  - after an OOM kill, wait 5 seconds for the next kill   (me)
  - agpgart_be fix for hashed waitqueues                  (William Lee Irwin)
rmap 11:
  - fix stupid logic inversion bug in wakeup_kswapd()     (Andrew Morton)
  - fix it again in the morning                           (me)
  - add #ifdef BROKEN_PPC_PTE_ALLOC_ONE to rmap.h, it
    seems PPC calls pte_alloc() before mem_map[] init     (me)
  - disable the debugging code in rmap.c ... the code
    is working and people are running benchmarks          (me)
  - let the slab cache shrink functions return a value
    to help prevent early OOM killing                     (Ed Tomlinson)
  - also, don't call the OOM code if we have enough
    free pages                                            (me)
  - move the call to lru_cache_del into __free_pages_ok   (Ben LaHaise)
  - replace the per-page waitqueue with a hashed
    waitqueue, reduces size of struct page from 64
    bytes to 52 bytes (48 bytes on non-highmem machines)  (William Lee Irwin)
rmap 10:
  - fix the livelock for real (yeah right), turned out
    to be a stupid bug in page_launder_zone()             (me)
  - to make sure the VM subsystem doesn't monopolise
    the CPU, let kswapd and some apps sleep a bit under
    heavy stress situations                               (me)
  - let __GFP_HIGH allocations dig a little bit deeper
    into the free page pool, the SCSI layer seems fragile (me)
rmap 9:
  - improve comments all over the place                   (Michael Cohen)
  - don't panic if page_remove_rmap() cannot find the
    rmap in question, it's possible that the memory was
    PG_reserved and belonging to a driver, but the driver
    exited and cleared the PG_reserved bit                (me)
  - fix the VM livelock by replacing > by >= in a few
    critical places in the pageout code                   (me)
  - treat the reclaiming of an inactive_clean page like
    allocating a new page, calling try_to_free_pages()
    and/or fixup_freespace() if required                  (me)
  - when low on memory, don't make things worse by
    doing swapin_readahead                                (me)
rmap 8:
  - add ANY_ZONE to the balancing functions to improve
    kswapd's balancing a bit                              (me)
  - regularize some of the maximum loop bounds in
    vmscan.c for cosmetic purposes                        (William Lee Irwin)
  - move page_address() to architecture-independent
    code, now the removal of page->virtual is portable    (William Lee Irwin)
  - speed up free_area_init_core() by doing a single
    pass over the pages and not using atomic ops          (William Lee Irwin)
  - documented the buddy allocator in page_alloc.c        (William Lee Irwin)
rmap 7:
  - clean up and document vmscan.c                        (me)
  - reduce size of page struct, part one                  (William Lee Irwin)
  - add rmap.h for other archs (untested, not for ARM)    (me)
rmap 6:
  - make the active and inactive_dirty list per zone,
    this is finally possible because we can free pages
    based on their physical address                       (William Lee Irwin)
  - cleaned up William's code a bit                       (me)
  - turn some defines into inlines and move those to
    mm_inline.h (the includes are a mess ...)             (me)
  - improve the VM balancing a bit                        (me)
  - add back inactive_target to /proc/meminfo             (me)
rmap 5:
  - fixed recursive buglet, introduced by directly
    editing the patch for making rmap 4 ;)))              (me)
rmap 4:
  - look at the referenced bits in page tables            (me)
rmap 3:
  - forgot one FASTCALL definition                        (me)
rmap 2:
  - teach try_to_unmap_one() about mremap()               (me)
  - don't assign swap space to pages with buffers         (me)
  - make the rmap.c functions FASTCALL / inline           (me)
rmap 1:
  - fix the swap leak in rmap 0                           (Dave McCracken)
rmap 0:
  - port of reverse mapping VM to 2.4.16                  (me)

Rik
-- 
"Linux holds advantages over the single-vendor commercial OS"
    -- Microsoft's "Competing with Linux" document

http://www.surriel.com/		http://distro.conectiva.com/

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Re: [PATCH *] rmap VM 12d

[Jens Axboe]

On Thu, Feb 07 2002, Rik van Riel wrote:
>   - fix starvation issue in get_request_wait()

I'm currently fixing this (non-trivial) problem in 2.5, I'll do a 2.4
back port afterwards. Hopefully with the same structure, if it doesn't
become too big a change.

-- 
Jens Axboe

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