[PATCH v4 0/7] Enable queued rwlock and queued spinlock for SPARC

[Babu Moger]

This series of patches enables queued rwlock and queued spinlock support
for SPARC. These features were introduced some time ago in upstream.
Here are some of the earlier discussions.
https://lwn.net/Articles/572765/
https://lwn.net/Articles/582200/
https://lwn.net/Articles/561775/
https://lwn.net/Articles/590243/

Tests: Ran AIM7 benchmark to verify the performance on various workloads.
https://github.com/davidlohr/areaim. Same benchmark was used when this
feature was introduced and enabled on x86. Here are the test results.

Kernel				4.11.0-rc6     4.11.0-rc6 + 	Change
				baseline	queued locks
			      (Avg No.of jobs) (Avg No.of jobs)
Workload
High systime 10-100 user	 17290.48	 17295.18	+0.02
High systime 200-1000 users	109814.95	110248.87	+0.39
High systime 1200-2000 users	107912.40	127923.16	+18.54

Disk IO 10-100 users		168910.16	158834.17	-5.96
Disk IO 200-1000 users		242781.74	281285.80	+15.85
Disk IO 1200-2000 users		228518.23	218421.23	-4.41

Disk IO 10-100 users		183933.77	207928.67	+13.04
Disk IO 200-1000 users		491981.56	500162.33	+1.66
Disk IO 1200-2000 users		463395.66	467312.70	+0.84

fserver 10-100 users		254177.53	270283.08	+6.33
fserver IO 200-1000 users	269017.35	324812.2	+20.74
fserver IO 1200-2000 users	229538.87	284713.77	+24.03

Disk I/O results are little bit in negative territory. But majority of the 
performance changes are in positive and it is significant in some cases.

Changes:
v3 -> v4:
 1. Took care of Geert Uytterhoeven's comment about patch #3(def_bool y)
 2. Working on separate patch sets to define CPU_BIG_ENDIAN for all the 
    default big endian architectures based on feedback from Geert and Arnd.

v2 -> v3:
 1. Rebased the patches on top of 4.12-rc2.
 2. Re-ordered the patch #1 and patch #2. That is the same order I have seen 
    the issues. So, it should be addressed in the same order. Patch #1 removes
    the check __LINUX_SPINLOCK_TYPES_H. Patch #2 addreses the compile error
    with qrwlock.c. This addresses the comments from Dave Miller on v2.

v1 -> v2:
Addressed the comments from David Miller.
1. Added CPU_BIG_ENDIAN for all SPARC
2. Removed #ifndef __LINUX_SPINLOCK_TYPES_H guard from spinlock_types.h
3. Removed check for CONFIG_QUEUED_RWLOCKS in SPARC64 as it is the 
   default definition for SPARC64 now. Cleaned-up the previous arch_read_xxx
   and arch_write_xxx definitions as it is defined now in qrwlock.h.
4. Removed check for CONFIG_QUEUED_SPINLOCKS in SPARC64 as it is the default
   definition now for SPARC64 now. Cleaned-up the previous arch_spin_xxx
   definitions as it is defined in qspinlock.h. 

v1: Initial version

Babu Moger (7):
  arch/sparc: Remove the check #ifndef __LINUX_SPINLOCK_TYPES_H
  kernel/locking: Fix compile error with qrwlock.c
  arch/sparc: Define config parameter CPU_BIG_ENDIAN
  arch/sparc: Introduce cmpxchg_u8 SPARC
  arch/sparc: Enable queued rwlocks for SPARC
  arch/sparc: Introduce xchg16 for SPARC
  arch/sparc: Enable queued spinlock support for SPARC

 arch/sparc/Kconfig                      |    5 +
 arch/sparc/include/asm/cmpxchg_64.h     |   76 ++++++++++--
 arch/sparc/include/asm/qrwlock.h        |    7 +
 arch/sparc/include/asm/qspinlock.h      |    7 +
 arch/sparc/include/asm/spinlock_64.h    |  208 +------------------------------
 arch/sparc/include/asm/spinlock_types.h |   12 ++-
 kernel/locking/qrwlock.c                |    1 +
 7 files changed, 97 insertions(+), 219 deletions(-)
 create mode 100644 arch/sparc/include/asm/qrwlock.h
 create mode 100644 arch/sparc/include/asm/qspinlock.h