Hi,
It seems the cause for the livelock wasn't what I thought it was
for rmap-9, I finally ran into a piece of old, broken code, right
in the middle of page_launder(). Now the machine boots and runs
decently with only 1 MB of swappable memory left (the rest consumed
by the swap bitmap, the kernel itself, profiling buffer, ...).
This version seems to work nicely even under some pretty strange
corner cases.
The 10th 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-10
and http://linuxvm.bkbits.net/
My big TODO items for a next release are:
- fix page_launder() so it doesn't submit the whole
inactive_dirty list for writeout in one go
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
--
Shortwave goes a long way: irc.starchat.net #swl
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On Wed, 2 Jan 2002, Rik van Riel wrote:
> The 10th 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-10
> and http://linuxvm.bkbits.net/
Of course, Andrew Morton found a logic inversion bug in
wakeup_kswapd() which could cause system hangs. Please
get this patch instead:
http://surriel.com/patches/2.4/2.4.17-rmap-10a
Rik
--
Shortwave goes a long way: irc.starchat.net #swl
http://www.surriel.com/ http://distro.conectiva.com/