into samba.org:/scratch/anton/linux-2.5_ppc64_work

into samba.org:/scratch/anton/linux-2.5_ppc64_work

into samba.org:/scratch/anton/linux-2.5_ppc64_work

into samba.org:/scratch/anton/linux-2.5_ppc64_work

into penguin.transmeta.com:/home/penguin/torvalds/repositories/kernel/linux

SGI Modid: 2.5.x-xfs:slinx:134222a

SGI Modid: 2.5.x-xfs:slinx:134216a

SGI Modid: 2.5.x-xfs:slinx:134187a

SGI Modid: 2.5.x-xfs:slinx:134185a

SGI Modid: 2.5.x-xfs:slinx:134098a

around in active state for as long as possible. This allows us to
coalesce several transactions into one buffer and reduce the disk
traffic.

SGI Modid: 2.5.x-xfs:slinx:134077a

SGI Modid: 2.5.x-xfs:slinx:134179a

SGI Modid: 2.5.x-xfs:slinx:133408a

remove the callback processing from the log write path, we only
do callbacks on I/O completion now.

SGI Modid: 2.5.x-xfs:slinx:133285a

SGI Modid: 2.5.x-xfs:slinx:133254a

SGI Modid: 2.5.x-xfs:slinx:134176a

SGI Modid: 2.5.x-xfs:slinx:132911a

SGI Modid: 2.5.x-xfs:slinx:134172a

SGI Modid: 2.5.x-xfs:slinx:134113a

SGI Modid: 2.5.x-xfs:slinx:134107a

SGI Modid: 2.5.x-xfs:slinx:134068a

data structures (sb,agf,agi,agfl) are now sector size aware.  Cleaned up
the early mount code dealing with log devices and logsectsize.

SGI Modid: 2.5.x-xfs:slinx:134065a

SGI Modid: 2.5.x-xfs:slinx:134064a

SGI Modid: 2.5.x-xfs:slinx:134059a

SGI Modid: 2.5.x-xfs:slinx:134013a

SGI Modid: 2.5.x-xfs:slinx:133971a

Make old 32-bit getdents() look more like the updated
getdents64 for maintainability.

2.5 is 20% slower than 2.4 in an AIM9 test which is just running
readdir across /bin.  A lot of this is due to lots of tiny calls to
copy_to_user() in fs/readdir.c.  The patch speeds up that test by 50%,
so it's comfortably faster than 2.4.

Also, there were lots of unchecked copy_to_user() and put_user() calls
in there.  Fixed all that up as well.

The patch assumes that each arch has a working 64-bit put_user(), which
appears to be the case.

If a page is "freed" while in the deferred-lru-addition queue, the
final reference to it is the deferred lru addition queue.  When that
queue gets spilled onto the LRU, the page is actually freed.

Which is all expected and natural and works fine - it's a weird case.

But one of the AIM9 tests was taking a 20% performance hit (relative to
2.4) because it was going into the page allocator for new pages while
cache-hot pages were languishiung out in the deferred-addition queue.

So the patch changes things so that we spill the CPU's
deferred-lru-addition queue before starting to free pages.  This way,
the recently-used pages actually make it to the hot/cold lists and are
available for new allocations.

It gets back 15 of the lost 20%.  The other 5% is lost to the general
additional complexity of all this stuff.  (But we're 250% faster than
2.4 when running four instances of the test on 4-way).

This patch optimises the truncate of a zero-length file, which is a
sufficiently common case to justify the extra test-n-branch.

It does this by skipping the entire call into the fs if i_size is not
being altered.

The AIM9 `open_clo' test just loops, creating and unlinking a file.
This patch speeds it up 50% for ext2, 600% for reiserfs.

The buffer-stripping code gets upset when it sees a non-uptodate buffer
against an uptodate page.  This happens because the write end_io
handler clears BH_Uptodate.

Add a buffer_req() test to suppress these warnings.

Patch from Hugh Dickins and Robert Love.

Fixes up the PF_MEMDIE handling so that it actually works.

(PF_MEMDIE allows an oom-killed task to use the emergency memory
reserves so that it can actually get out of the page allocator and
die)

2.5's signal delivery is 20% slower than 2.4.  A signal send/handle
cycle is performing a total of 24 copy_*_user() calls, and
copy_*_user() got optimised for large copies.

The patch reduces that to six copy_*_user() calls, and gets us up to
about 5% slower than 2.4.  We'd have to go back to some additional
inlined copy_user() code to get the last 3% back.  And HZ=100 to get
the 2% back.

It is noteworthy that the benchmark is not using float at all during
the body of the test, yet the kernel is still doing all that floating
point stuff.

Patch from Mingming Cao <cmm@us.ibm.com>

- ipc_lock() need a read_barrier_depends() to prevent indexing
  uninitialized new array on the read side.  This is corresponding to
  the write memory barrier added in grow_ary() from Dipankar's patch to
  prevent indexing uninitialized array.

- Replaced "wmb()" in IPC code with "smp_wmb()"."wmb()" produces a
  full write memory barrier in both UP and SMP kernels, while
  "smp_wmb()" provides a full write memory barrier in an SMP kernel,
  but only a compiler directive in a UP kernel.  The same change are
  made for "rmb()".

- Removed rmb() in ipc_get().  We do not need a read memory barrier
  there since ipc_get() is protected by ipc_ids.sem semaphore.

- Added more comments about why write barriers and read barriers are
  needed (or not needed) here or there.

With some workloads a large number of pages coming off the LRU are
pinned blockdev pagecache - things like ext2 group descriptors, pages
which have buffers in the per-cpu buffer LRUs, etc.

They keep churning around the inactive list, reducing the overall page
reclaim effectiveness.

So move these pages onto the active list.