slub: disallow changing cpu_partial from userspace for debug caches …

For caches with debugging enabled, "slub: Switch per cpu partial page
support off for debugging" changes cpu_partial to 0.  It shouldn't be
tunable from userspace for such caches, otherwise the same accounting
issues arise during validation.

This patch disallows tuning /sys/kernel/slab/cache/cpu_partial to be non-
zero for caches with debugging enabled.

Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
slub: min order when debug_guardpage_minorder > 0

Disable slub debug facilities and allocate slabs at minimal order when
debug_guardpage_minorder > 0 to increase probability to catch random
memory corruption by cpu exception.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm,slub,x86: decouple size of struct page from CONFIG_CMPXCHG_LOCAL

While implementing cmpxchg_double() on s390 I realized that we don't set
CONFIG_CMPXCHG_LOCAL despite the fact that we have support for it.

However setting that option will increase the size of struct page by
eight bytes on 64 bit, which we certainly do not want.  Also, it doesn't
make sense that a present cpu feature should increase the size of struct
page.

Besides that it looks like the dependency to CMPXCHG_LOCAL is wrong and
that it should depend on CMPXCHG_DOUBLE instead.

This patch:

If an architecture supports CMPXCHG_LOCAL this shouldn't result
automatically in larger struct pages if the SLUB allocator is used.
Instead introduce a new config option "HAVE_ALIGNED_STRUCT_PAGE" which
can be selected if a double word aligned struct page is required.  Also
update x86 Kconfig so that it should work as before.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Conflicts:
	arch/Kconfig

Change-Id: Ic501dc1409806cce67a39ac924c02a807d786bc3
mm,x86,um: move CMPXCHG_DOUBLE config option

Move CMPXCHG_DOUBLE and rename it to HAVE_CMPXCHG_DOUBLE so architectures
can simply select the option if it is supported.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Conflicts:
	arch/Kconfig
	arch/x86/Kconfig
	arch/x86/Kconfig.cpu
	arch/x86/um/Kconfig

Change-Id: I4f2c9f142ceb5bd612b85c55cebdbe5bd80bab6d
Revert "slub: min order when debug_guardpage_minorder > 0"
slub: prefetch next freelist pointer in slab_alloc()

Recycling a page is a problem, since freelist link chain is hot on
cpu(s) which freed objects, and possibly very cold on cpu currently
owning slab.

Adding a prefetch of cache line containing the pointer to next object in
slab_alloc() helps a lot in many workloads, in particular on assymetric
ones (allocations done on one cpu, frees on another cpus). Added cost is
three machine instructions only.

Examples on my dual socket quad core ht machine (Intel CPU E5540
@2.53GHz) (16 logical cpus, 2 memory nodes), 64bit kernel.

Before patch :

 Performance counter stats for 'hackbench 50 process 4000' (32 runs):

     327577,471718 task-clock                #   15,821 CPUs utilized            ( +-  0,64% )
        28 866 491 context-switches          #    0,088 M/sec                    ( +-  1,80% )
         1 506 929 CPU-migrations            #    0,005 M/sec                    ( +-  3,24% )
           127 151 page-faults               #    0,000 M/sec                    ( +-  0,16% )
   829 399 813 448 cycles                    #    2,532 GHz                      ( +-  0,64% )
   580 664 691 740 stalled-cycles-frontend   #   70,01% frontend cycles idle     ( +-  0,71% )
   197 431 700 448 stalled-cycles-backend    #   23,80% backend  cycles idle     ( +-  1,03% )
   503 548 648 975 instructions              #    0,61  insns per cycle
                                             #    1,15  stalled cycles per insn  ( +-  0,46% )
    95 780 068 471 branches                  #  292,389 M/sec                    ( +-  0,48% )
     1 426 407 916 branch-misses             #    1,49% of all branches          ( +-  1,35% )

      20,705679994 seconds time elapsed                                          ( +-  0,64% )

After patch :

 Performance counter stats for 'hackbench 50 process 4000' (32 runs):

     286236,542804 task-clock                #   15,786 CPUs utilized            ( +-  1,32% )
        19 703 372 context-switches          #    0,069 M/sec                    ( +-  4,99% )
         1 658 249 CPU-migrations            #    0,006 M/sec                    ( +-  6,62% )
           126 776 page-faults               #    0,000 M/sec                    ( +-  0,12% )
   724 636 593 213 cycles                    #    2,532 GHz                      ( +-  1,32% )
   499 320 714 837 stalled-cycles-frontend   #   68,91% frontend cycles idle     ( +-  1,47% )
   156 555 126 809 stalled-cycles-backend    #   21,60% backend  cycles idle     ( +-  2,22% )
   463 897 792 661 instructions              #    0,64  insns per cycle
                                             #    1,08  stalled cycles per insn  ( +-  0,94% )
    87 717 352 563 branches                  #  306,451 M/sec                    ( +-  0,99% )
       941 738 280 branch-misses             #    1,07% of all branches          ( +-  3,35% )

      18,132070670 seconds time elapsed                                          ( +-  1,30% )

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
CC: Matt Mackall <mpm@selenic.com>
CC: David Rientjes <rientjes@google.com>
CC: "Alex,Shi" <alex.shi@intel.com>
CC: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
slub: include include for prefetch

Otherwise m68k breaks:

On Mon, 30 Jan 2012, Geert Uytterhoeven wrote:
> m68k/allmodconfig at http://kisskb.ellerman.id.au/kisskb/buildresult/5527349/
>
> mm/slub.c:274: error: implicit declaration of function 'prefetch'
>
> Sorry, didn't notice it earlier due to other build breakage in -next.

Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
slub: per cpu partial statistics change

This patch split the cpu_partial_free into 2 parts: cpu_partial_node, PCP refilling
times from node partial; and same name cpu_partial_free, PCP refilling times in
slab_free slow path. A new statistic 'cpu_partial_drain' is added to get PCP
drain to node partial times. These info are useful when do PCP tunning.

The slabinfo.c code is unchanged, since cpu_partial_node is not on slow path.

Signed-off-by: Alex Shi <alex.shi@intel.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

Conflicts:
	mm/slub.c

Change-Id: I627800e9eafad8f64940652f1409cb2fb4f53390