<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/include/linux/mmzone.h, branch v2.6.34</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>Merge branch 'for-next' into for-linus</title>
<updated>2010-03-08T15:55:37+00:00</updated>
<author>
<name>Jiri Kosina</name>
<email>jkosina@suse.cz</email>
</author>
<published>2010-03-08T15:55:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=318ae2edc3b29216abd8a2510f3f80b764f06858'/>
<id>318ae2edc3b29216abd8a2510f3f80b764f06858</id>
<content type='text'>
Conflicts:
	Documentation/filesystems/proc.txt
	arch/arm/mach-u300/include/mach/debug-macro.S
	drivers/net/qlge/qlge_ethtool.c
	drivers/net/qlge/qlge_main.c
	drivers/net/typhoon.c
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Conflicts:
	Documentation/filesystems/proc.txt
	arch/arm/mach-u300/include/mach/debug-macro.S
	drivers/net/qlge/qlge_ethtool.c
	drivers/net/qlge/qlge_main.c
	drivers/net/typhoon.c
</pre>
</div>
</content>
</entry>
<entry>
<title>mm: restore zone-&gt;all_unreclaimable to independence word</title>
<updated>2010-03-06T19:26:25+00:00</updated>
<author>
<name>KOSAKI Motohiro</name>
<email>kosaki.motohiro@jp.fujitsu.com</email>
</author>
<published>2010-03-05T21:41:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=93e4a89a8c987189b168a530a331ef6d0fcf07a7'/>
<id>93e4a89a8c987189b168a530a331ef6d0fcf07a7</id>
<content type='text'>
commit e815af95 ("change all_unreclaimable zone member to flags") changed
all_unreclaimable member to bit flag.  But it had an undesireble side
effect.  free_one_page() is one of most hot path in linux kernel and
increasing atomic ops in it can reduce kernel performance a bit.

Thus, this patch revert such commit partially. at least
all_unreclaimable shouldn't share memory word with other zone flags.

[akpm@linux-foundation.org: fix patch interaction]
Signed-off-by: KOSAKI Motohiro &lt;kosaki.motohiro@jp.fujitsu.com&gt;
Cc: David Rientjes &lt;rientjes@google.com&gt;
Cc: Wu Fengguang &lt;fengguang.wu@intel.com&gt;
Cc: KAMEZAWA Hiroyuki &lt;kamezawa.hiroyu@jp.fujitsu.com&gt;
Cc: Minchan Kim &lt;minchan.kim@gmail.com&gt;
Cc: Huang Shijie &lt;shijie8@gmail.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit e815af95 ("change all_unreclaimable zone member to flags") changed
all_unreclaimable member to bit flag.  But it had an undesireble side
effect.  free_one_page() is one of most hot path in linux kernel and
increasing atomic ops in it can reduce kernel performance a bit.

Thus, this patch revert such commit partially. at least
all_unreclaimable shouldn't share memory word with other zone flags.

[akpm@linux-foundation.org: fix patch interaction]
Signed-off-by: KOSAKI Motohiro &lt;kosaki.motohiro@jp.fujitsu.com&gt;
Cc: David Rientjes &lt;rientjes@google.com&gt;
Cc: Wu Fengguang &lt;fengguang.wu@intel.com&gt;
Cc: KAMEZAWA Hiroyuki &lt;kamezawa.hiroyu@jp.fujitsu.com&gt;
Cc: Minchan Kim &lt;minchan.kim@gmail.com&gt;
Cc: Huang Shijie &lt;shijie8@gmail.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'x86-bootmem-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip</title>
<updated>2010-03-03T16:15:05+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2010-03-03T16:15:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=a626b46e17d0762d664ce471d40bc506b6e721ab'/>
<id>a626b46e17d0762d664ce471d40bc506b6e721ab</id>
<content type='text'>
* 'x86-bootmem-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (30 commits)
  early_res: Need to save the allocation name in drop_range_partial()
  sparsemem: Fix compilation on PowerPC
  early_res: Add free_early_partial()
  x86: Fix non-bootmem compilation on PowerPC
  core: Move early_res from arch/x86 to kernel/
  x86: Add find_fw_memmap_area
  Move round_up/down to kernel.h
  x86: Make 32bit support NO_BOOTMEM
  early_res: Enhance check_and_double_early_res
  x86: Move back find_e820_area to e820.c
  x86: Add find_early_area_size
  x86: Separate early_res related code from e820.c
  x86: Move bios page reserve early to head32/64.c
  sparsemem: Put mem map for one node together.
  sparsemem: Put usemap for one node together
  x86: Make 64 bit use early_res instead of bootmem before slab
  x86: Only call dma32_reserve_bootmem 64bit !CONFIG_NUMA
  x86: Make early_node_mem get mem &gt; 4 GB if possible
  x86: Dynamically increase early_res array size
  x86: Introduce max_early_res and early_res_count
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
* 'x86-bootmem-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (30 commits)
  early_res: Need to save the allocation name in drop_range_partial()
  sparsemem: Fix compilation on PowerPC
  early_res: Add free_early_partial()
  x86: Fix non-bootmem compilation on PowerPC
  core: Move early_res from arch/x86 to kernel/
  x86: Add find_fw_memmap_area
  Move round_up/down to kernel.h
  x86: Make 32bit support NO_BOOTMEM
  early_res: Enhance check_and_double_early_res
  x86: Move back find_e820_area to e820.c
  x86: Add find_early_area_size
  x86: Separate early_res related code from e820.c
  x86: Move bios page reserve early to head32/64.c
  sparsemem: Put mem map for one node together.
  sparsemem: Put usemap for one node together
  x86: Make 64 bit use early_res instead of bootmem before slab
  x86: Only call dma32_reserve_bootmem 64bit !CONFIG_NUMA
  x86: Make early_node_mem get mem &gt; 4 GB if possible
  x86: Dynamically increase early_res array size
  x86: Introduce max_early_res and early_res_count
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>percpu: add __percpu sparse annotations to core kernel subsystems</title>
<updated>2010-02-17T02:17:38+00:00</updated>
<author>
<name>Tejun Heo</name>
<email>tj@kernel.org</email>
</author>
<published>2010-02-02T05:38:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=43cf38eb5cea91245502df3fcee4dbfc1c74dd1c'/>
<id>43cf38eb5cea91245502df3fcee4dbfc1c74dd1c</id>
<content type='text'>
Add __percpu sparse annotations to core subsystems.

These annotations are to make sparse consider percpu variables to be
in a different address space and warn if accessed without going
through percpu accessors.  This patch doesn't affect normal builds.

Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Reviewed-by: Christoph Lameter &lt;cl@linux-foundation.org&gt;
Acked-by: Paul E. McKenney &lt;paulmck@linux.vnet.ibm.com&gt;
Cc: Jens Axboe &lt;axboe@kernel.dk&gt;
Cc: linux-mm@kvack.org
Cc: Rusty Russell &lt;rusty@rustcorp.com.au&gt;
Cc: Dipankar Sarma &lt;dipankar@in.ibm.com&gt;
Cc: Peter Zijlstra &lt;a.p.zijlstra@chello.nl&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Eric Biederman &lt;ebiederm@xmission.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Add __percpu sparse annotations to core subsystems.

These annotations are to make sparse consider percpu variables to be
in a different address space and warn if accessed without going
through percpu accessors.  This patch doesn't affect normal builds.

Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Reviewed-by: Christoph Lameter &lt;cl@linux-foundation.org&gt;
Acked-by: Paul E. McKenney &lt;paulmck@linux.vnet.ibm.com&gt;
Cc: Jens Axboe &lt;axboe@kernel.dk&gt;
Cc: linux-mm@kvack.org
Cc: Rusty Russell &lt;rusty@rustcorp.com.au&gt;
Cc: Dipankar Sarma &lt;dipankar@in.ibm.com&gt;
Cc: Peter Zijlstra &lt;a.p.zijlstra@chello.nl&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Eric Biederman &lt;ebiederm@xmission.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>x86: Make 64 bit use early_res instead of bootmem before slab</title>
<updated>2010-02-12T17:41:59+00:00</updated>
<author>
<name>Yinghai Lu</name>
<email>yinghai@kernel.org</email>
</author>
<published>2010-02-10T09:20:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=08677214e318297f228237be0042aac754f48f1d'/>
<id>08677214e318297f228237be0042aac754f48f1d</id>
<content type='text'>
Finally we can use early_res to replace bootmem for x86_64 now.

Still can use CONFIG_NO_BOOTMEM to enable it or not.

-v2: fix 32bit compiling about MAX_DMA32_PFN
-v3: folded bug fix from LKML message below

Signed-off-by: Yinghai Lu &lt;yinghai@kernel.org&gt;
LKML-Reference: &lt;4B747239.4070907@kernel.org&gt;
Signed-off-by: H. Peter Anvin &lt;hpa@zytor.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Finally we can use early_res to replace bootmem for x86_64 now.

Still can use CONFIG_NO_BOOTMEM to enable it or not.

-v2: fix 32bit compiling about MAX_DMA32_PFN
-v3: folded bug fix from LKML message below

Signed-off-by: Yinghai Lu &lt;yinghai@kernel.org&gt;
LKML-Reference: &lt;4B747239.4070907@kernel.org&gt;
Signed-off-by: H. Peter Anvin &lt;hpa@zytor.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Fix misspellings of "invocation" in comments.</title>
<updated>2010-02-04T10:55:45+00:00</updated>
<author>
<name>Adam Buchbinder</name>
<email>adam.buchbinder@gmail.com</email>
</author>
<published>2009-12-11T21:35:40+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=2a61aa401638529cd4231f6106980d307fba98fa'/>
<id>2a61aa401638529cd4231f6106980d307fba98fa</id>
<content type='text'>
Some comments misspell "invocation"; this fixes them. No code
changes.

Signed-off-by: Adam Buchbinder &lt;adam.buchbinder@gmail.com&gt;
Signed-off-by: Jiri Kosina &lt;jkosina@suse.cz&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Some comments misspell "invocation"; this fixes them. No code
changes.

Signed-off-by: Adam Buchbinder &lt;adam.buchbinder@gmail.com&gt;
Signed-off-by: Jiri Kosina &lt;jkosina@suse.cz&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>this_cpu: Page allocator conversion</title>
<updated>2010-01-05T06:34:51+00:00</updated>
<author>
<name>Christoph Lameter</name>
<email>cl@linux-foundation.org</email>
</author>
<published>2010-01-05T06:34:51+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=99dcc3e5a94ed491fbef402831d8c0bbb267f995'/>
<id>99dcc3e5a94ed491fbef402831d8c0bbb267f995</id>
<content type='text'>
Use the per cpu allocator functionality to avoid per cpu arrays in struct zone.

This drastically reduces the size of struct zone for systems with large
amounts of processors and allows placement of critical variables of struct
zone in one cacheline even on very large systems.

Another effect is that the pagesets of one processor are placed near one
another. If multiple pagesets from different zones fit into one cacheline
then additional cacheline fetches can be avoided on the hot paths when
allocating memory from multiple zones.

Bootstrap becomes simpler if we use the same scheme for UP, SMP, NUMA. #ifdefs
are reduced and we can drop the zone_pcp macro.

Hotplug handling is also simplified since cpu alloc can bring up and
shut down cpu areas for a specific cpu as a whole. So there is no need to
allocate or free individual pagesets.

V7-V8:
- Explain chicken egg dilemmna with percpu allocator.

V4-V5:
- Fix up cases where per_cpu_ptr is called before irq disable
- Integrate the bootstrap logic that was separate before.

tj: Build failure in pageset_cpuup_callback() due to missing ret
    variable fixed.

Reviewed-by: Mel Gorman &lt;mel@csn.ul.ie&gt;
Signed-off-by: Christoph Lameter &lt;cl@linux-foundation.org&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Use the per cpu allocator functionality to avoid per cpu arrays in struct zone.

This drastically reduces the size of struct zone for systems with large
amounts of processors and allows placement of critical variables of struct
zone in one cacheline even on very large systems.

Another effect is that the pagesets of one processor are placed near one
another. If multiple pagesets from different zones fit into one cacheline
then additional cacheline fetches can be avoided on the hot paths when
allocating memory from multiple zones.

Bootstrap becomes simpler if we use the same scheme for UP, SMP, NUMA. #ifdefs
are reduced and we can drop the zone_pcp macro.

Hotplug handling is also simplified since cpu alloc can bring up and
shut down cpu areas for a specific cpu as a whole. So there is no need to
allocate or free individual pagesets.

V7-V8:
- Explain chicken egg dilemmna with percpu allocator.

V4-V5:
- Fix up cases where per_cpu_ptr is called before irq disable
- Integrate the bootstrap logic that was separate before.

tj: Build failure in pageset_cpuup_callback() due to missing ret
    variable fixed.

Reviewed-by: Mel Gorman &lt;mel@csn.ul.ie&gt;
Signed-off-by: Christoph Lameter &lt;cl@linux-foundation.org&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>kbuild: move bounds.h to include/generated</title>
<updated>2009-12-12T12:08:14+00:00</updated>
<author>
<name>Sam Ravnborg</name>
<email>sam@ravnborg.org</email>
</author>
<published>2009-04-19T19:57:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=01fc0ac198eabcbf460e1ed058860a935b6c2c9a'/>
<id>01fc0ac198eabcbf460e1ed058860a935b6c2c9a</id>
<content type='text'>
Signed-off-by: Sam Ravnborg &lt;sam@ravnborg.org&gt;
Cc: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Signed-off-by: Michal Marek &lt;mmarek@suse.cz&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Signed-off-by: Sam Ravnborg &lt;sam@ravnborg.org&gt;
Cc: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Signed-off-by: Michal Marek &lt;mmarek@suse.cz&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sysctl: remove "struct file *" argument of -&gt;proc_handler</title>
<updated>2009-09-24T14:21:04+00:00</updated>
<author>
<name>Alexey Dobriyan</name>
<email>adobriyan@gmail.com</email>
</author>
<published>2009-09-23T22:57:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=8d65af789f3e2cf4cfbdbf71a0f7a61ebcd41d38'/>
<id>8d65af789f3e2cf4cfbdbf71a0f7a61ebcd41d38</id>
<content type='text'>
It's unused.

It isn't needed -- read or write flag is already passed and sysctl
shouldn't care about the rest.

It _was_ used in two places at arch/frv for some reason.

Signed-off-by: Alexey Dobriyan &lt;adobriyan@gmail.com&gt;
Cc: David Howells &lt;dhowells@redhat.com&gt;
Cc: "Eric W. Biederman" &lt;ebiederm@xmission.com&gt;
Cc: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Ralf Baechle &lt;ralf@linux-mips.org&gt;
Cc: Martin Schwidefsky &lt;schwidefsky@de.ibm.com&gt;
Cc: Ingo Molnar &lt;mingo@elte.hu&gt;
Cc: "David S. Miller" &lt;davem@davemloft.net&gt;
Cc: James Morris &lt;jmorris@namei.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
It's unused.

It isn't needed -- read or write flag is already passed and sysctl
shouldn't care about the rest.

It _was_ used in two places at arch/frv for some reason.

Signed-off-by: Alexey Dobriyan &lt;adobriyan@gmail.com&gt;
Cc: David Howells &lt;dhowells@redhat.com&gt;
Cc: "Eric W. Biederman" &lt;ebiederm@xmission.com&gt;
Cc: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Ralf Baechle &lt;ralf@linux-mips.org&gt;
Cc: Martin Schwidefsky &lt;schwidefsky@de.ibm.com&gt;
Cc: Ingo Molnar &lt;mingo@elte.hu&gt;
Cc: "David S. Miller" &lt;davem@davemloft.net&gt;
Cc: James Morris &lt;jmorris@namei.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>page-allocator: split per-cpu list into one-list-per-migrate-type</title>
<updated>2009-09-22T14:17:39+00:00</updated>
<author>
<name>Mel Gorman</name>
<email>mel@csn.ul.ie</email>
</author>
<published>2009-09-22T00:03:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=5f8dcc21211a3d4e3a7a5ca366b469fb88117f61'/>
<id>5f8dcc21211a3d4e3a7a5ca366b469fb88117f61</id>
<content type='text'>
The following two patches remove searching in the page allocator fast-path
by maintaining multiple free-lists in the per-cpu structure.  At the time
the search was introduced, increasing the per-cpu structures would waste a
lot of memory as per-cpu structures were statically allocated at
compile-time.  This is no longer the case.

The patches are as follows. They are based on mmotm-2009-08-27.

Patch 1 adds multiple lists to struct per_cpu_pages, one per
	migratetype that can be stored on the PCP lists.

Patch 2 notes that the pcpu drain path check empty lists multiple times. The
	patch reduces the number of checks by maintaining a count of free
	lists encountered. Lists containing pages will then free multiple
	pages in batch

The patches were tested with kernbench, netperf udp/tcp, hackbench and
sysbench.  The netperf tests were not bound to any CPU in particular and
were run such that the results should be 99% confidence that the reported
results are within 1% of the estimated mean.  sysbench was run with a
postgres background and read-only tests.  Similar to netperf, it was run
multiple times so that it's 99% confidence results are within 1%.  The
patches were tested on x86, x86-64 and ppc64 as

x86:	Intel Pentium D 3GHz with 8G RAM (no-brand machine)
	kernbench	- No significant difference, variance well within noise
	netperf-udp	- 1.34% to 2.28% gain
	netperf-tcp	- 0.45% to 1.22% gain
	hackbench	- Small variances, very close to noise
	sysbench	- Very small gains

x86-64:	AMD Phenom 9950 1.3GHz with 8G RAM (no-brand machine)
	kernbench	- No significant difference, variance well within noise
	netperf-udp	- 1.83% to 10.42% gains
	netperf-tcp	- No conclusive until buffer &gt;= PAGE_SIZE
				4096	+15.83%
				8192	+ 0.34% (not significant)
				16384	+ 1%
	hackbench	- Small gains, very close to noise
	sysbench	- 0.79% to 1.6% gain

ppc64:	PPC970MP 2.5GHz with 10GB RAM (it's a terrasoft powerstation)
	kernbench	- No significant difference, variance well within noise
	netperf-udp	- 2-3% gain for almost all buffer sizes tested
	netperf-tcp	- losses on small buffers, gains on larger buffers
			  possibly indicates some bad caching effect.
	hackbench	- No significant difference
	sysbench	- 2-4% gain

This patch:

Currently the per-cpu page allocator searches the PCP list for pages of
the correct migrate-type to reduce the possibility of pages being
inappropriate placed from a fragmentation perspective.  This search is
potentially expensive in a fast-path and undesirable.  Splitting the
per-cpu list into multiple lists increases the size of a per-cpu structure
and this was potentially a major problem at the time the search was
introduced.  These problem has been mitigated as now only the necessary
number of structures is allocated for the running system.

This patch replaces a list search in the per-cpu allocator with one list
per migrate type.  The potential snag with this approach is when bulk
freeing pages.  We round-robin free pages based on migrate type which has
little bearing on the cache hotness of the page and potentially checks
empty lists repeatedly in the event the majority of PCP pages are of one
type.

Signed-off-by: Mel Gorman &lt;mel@csn.ul.ie&gt;
Acked-by: Nick Piggin &lt;npiggin@suse.de&gt;
Cc: Christoph Lameter &lt;cl@linux-foundation.org&gt;
Cc: Minchan Kim &lt;minchan.kim@gmail.com&gt;
Cc: Pekka Enberg &lt;penberg@cs.helsinki.fi&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
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The following two patches remove searching in the page allocator fast-path
by maintaining multiple free-lists in the per-cpu structure.  At the time
the search was introduced, increasing the per-cpu structures would waste a
lot of memory as per-cpu structures were statically allocated at
compile-time.  This is no longer the case.

The patches are as follows. They are based on mmotm-2009-08-27.

Patch 1 adds multiple lists to struct per_cpu_pages, one per
	migratetype that can be stored on the PCP lists.

Patch 2 notes that the pcpu drain path check empty lists multiple times. The
	patch reduces the number of checks by maintaining a count of free
	lists encountered. Lists containing pages will then free multiple
	pages in batch

The patches were tested with kernbench, netperf udp/tcp, hackbench and
sysbench.  The netperf tests were not bound to any CPU in particular and
were run such that the results should be 99% confidence that the reported
results are within 1% of the estimated mean.  sysbench was run with a
postgres background and read-only tests.  Similar to netperf, it was run
multiple times so that it's 99% confidence results are within 1%.  The
patches were tested on x86, x86-64 and ppc64 as

x86:	Intel Pentium D 3GHz with 8G RAM (no-brand machine)
	kernbench	- No significant difference, variance well within noise
	netperf-udp	- 1.34% to 2.28% gain
	netperf-tcp	- 0.45% to 1.22% gain
	hackbench	- Small variances, very close to noise
	sysbench	- Very small gains

x86-64:	AMD Phenom 9950 1.3GHz with 8G RAM (no-brand machine)
	kernbench	- No significant difference, variance well within noise
	netperf-udp	- 1.83% to 10.42% gains
	netperf-tcp	- No conclusive until buffer &gt;= PAGE_SIZE
				4096	+15.83%
				8192	+ 0.34% (not significant)
				16384	+ 1%
	hackbench	- Small gains, very close to noise
	sysbench	- 0.79% to 1.6% gain

ppc64:	PPC970MP 2.5GHz with 10GB RAM (it's a terrasoft powerstation)
	kernbench	- No significant difference, variance well within noise
	netperf-udp	- 2-3% gain for almost all buffer sizes tested
	netperf-tcp	- losses on small buffers, gains on larger buffers
			  possibly indicates some bad caching effect.
	hackbench	- No significant difference
	sysbench	- 2-4% gain

This patch:

Currently the per-cpu page allocator searches the PCP list for pages of
the correct migrate-type to reduce the possibility of pages being
inappropriate placed from a fragmentation perspective.  This search is
potentially expensive in a fast-path and undesirable.  Splitting the
per-cpu list into multiple lists increases the size of a per-cpu structure
and this was potentially a major problem at the time the search was
introduced.  These problem has been mitigated as now only the necessary
number of structures is allocated for the running system.

This patch replaces a list search in the per-cpu allocator with one list
per migrate type.  The potential snag with this approach is when bulk
freeing pages.  We round-robin free pages based on migrate type which has
little bearing on the cache hotness of the page and potentially checks
empty lists repeatedly in the event the majority of PCP pages are of one
type.

Signed-off-by: Mel Gorman &lt;mel@csn.ul.ie&gt;
Acked-by: Nick Piggin &lt;npiggin@suse.de&gt;
Cc: Christoph Lameter &lt;cl@linux-foundation.org&gt;
Cc: Minchan Kim &lt;minchan.kim@gmail.com&gt;
Cc: Pekka Enberg &lt;penberg@cs.helsinki.fi&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
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