kernel-fxtec-pro1x/arch
Jan Beulich a750036f35 x86: Fix write lock scalability 64-bit issue
With the write lock path simply subtracting RW_LOCK_BIAS there
is, on large systems, the theoretical possibility of overflowing
the 32-bit value that was used so far (namely if 128 or more
CPUs manage to do the subtraction, but don't get to do the
inverse addition in the failure path quickly enough).

A first measure is to modify RW_LOCK_BIAS itself - with the new
value chosen, it is good for up to 2048 CPUs each allowed to
nest over 2048 times on the read path without causing an issue.
Quite possibly it would even be sufficient to adjust the bias a
little further, assuming that allowing for significantly less
nesting would suffice.

However, as the original value chosen allowed for even more
nesting levels, to support more than 2048 CPUs (possible
currently only for 64-bit kernels) the lock itself gets widened
to 64 bits.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/4E258E0D020000780004E3F0@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-07-21 09:03:36 +02:00
..
alpha Merge branch 'setns' 2011-05-28 10:51:01 -07:00
arm Merge branch 'gpio/next' of git://git.secretlab.ca/git/linux-2.6 2011-05-28 10:56:34 -07:00
avr32 Merge branch 'setns' 2011-05-28 10:51:01 -07:00
blackfin Blackfin: debug-mmrs: include RSI_PID[4567] MMRs 2011-05-28 17:02:56 -04:00
cris Merge branch 'setns' 2011-05-28 10:51:01 -07:00
frv Merge branch 'setns' 2011-05-28 10:51:01 -07:00
h8300 Merge branch 'setns' 2011-05-28 10:51:01 -07:00
ia64 Merge branch 'setns' 2011-05-28 10:51:01 -07:00
m32r Merge branch 'setns' 2011-05-28 10:51:01 -07:00
m68k Merge branch 'setns' 2011-05-28 10:51:01 -07:00
microblaze Merge branch 'setns' 2011-05-28 10:51:01 -07:00
mips Merge branch 'setns' 2011-05-28 10:51:01 -07:00
mn10300 Merge branch 'setns' 2011-05-28 10:51:01 -07:00
parisc Merge branch 'setns' 2011-05-28 10:51:01 -07:00
powerpc Merge branch 'setns' 2011-05-28 10:51:01 -07:00
s390 [S390] mm: fix mmu_gather rework 2011-05-29 12:40:51 +02:00
score arch: remove CONFIG_GENERIC_FIND_{NEXT_BIT,BIT_LE,LAST_BIT} 2011-05-26 17:12:38 -07:00
sh Merge branch 'setns' 2011-05-28 10:51:01 -07:00
sparc Merge branch 'setns' 2011-05-28 10:51:01 -07:00
tile Merge git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile 2011-05-29 11:29:28 -07:00
um x86: Unify rwsem assembly implementation 2011-07-21 09:03:32 +02:00
unicore32 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/suspend-2.6 2011-05-27 14:27:34 -07:00
x86 x86: Fix write lock scalability 64-bit issue 2011-07-21 09:03:36 +02:00
xtensa Merge branch 'setns' 2011-05-28 10:51:01 -07:00
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