On 06/15/2016 01:22 PM, Peter Zijlstra wrote:
On Tue, Jun 14, 2016 at 06:48:05PM -0400, Waiman Long wrote:
Currently, when down_read() fails, the active read locking isn't undone
until the rwsem_down_read_failed() function grabs the wait_lock. If the
wait_lock is contended, it may takes a while
On 06/15/2016 01:12 PM, Peter Zijlstra wrote:
On Wed, Jun 15, 2016 at 09:56:59AM -0700, Davidlohr Bueso wrote:
On Tue, 14 Jun 2016, Waiman Long wrote:
+++ b/kernel/locking/osq_lock.c
@@ -115,7 +115,7 @@ bool osq_lock(struct optimistic_spin_queue *lock)
* cmpxchg in an attempt to undo
ock code.
Patch 6 enables readers to do optimistic spinning.
Waiman Long (6):
locking/osq: Make lock/unlock proper acquire/release barrier
locking/rwsem: Stop active read lock ASAP
locking/rwsem: Enable count-based spinning on reader
locking/rwsem: move down rwsem_down_read_failed funct
The osq_lock() and osq_unlock() function may not provide the necessary
acquire and release barrier in some cases. This patch makes sure
that the proper barriers are provided when osq_lock() is successful
or when osq_unlock() is called.
Signed-off-by: Waiman Long <waiman.l...@hpe.com>
---
On 06/14/2016 02:24 PM, Christoph Hellwig wrote:
On Tue, Jun 14, 2016 at 02:12:39PM -0400, Waiman Long wrote:
This patch enables reader optimistic spinning for inodes that are
under a DAX-based mount point.
On a 4-socket Haswell machine running on a 4.7-rc1 tip-based kernel,
the fio test
the default 4K (shift = 12) iteration
count.
Signed-off-by: Waiman Long <waiman.l...@hpe.com>
---
include/linux/rwsem.h | 21 -
kernel/locking/rwsem-xadd.c | 28 +++-
2 files changed, 39 insertions(+), 10 deletions(-)
diff --git a/include
--- --
randrw1210 MB/s 1352 MB/s +12%
randwrite 1622 MB/s 1710 MB/s +5.4%
The write-only microbench also showed improvement because some read
locking was done by the XFS code.
Signed-off-by: Waiman Long <waiman.l...@hpe.com>
---
%
Signed-off-by: Waiman Long <waiman.l...@hpe.com>
---
fs/xfs/xfs_icache.c |9 +
1 files changed, 9 insertions(+), 0 deletions(-)
diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index 99ee6ee..09f284f 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -71,6
This patch enables readers to optimistically spin when the
rspin_threshold is non-zero. That threshold value should only
be set when the lock owners of the rwsem are unlikely to go to
sleep. Otherwise enabling reader spinning may make the performance
worse in some cases.
Signed-off-by: Waiman
+ RWSEM_ACTIVE_READ_BIAS
Signed-off-by: Waiman Long <waiman.l...@hpe.com>
---
arch/alpha/include/asm/rwsem.h |7 ---
arch/ia64/include/asm/rwsem.h |6 +++---
arch/s390/include/asm/rwsem.h |6 +++---
arch/x86/include/asm/rwsem.h | 13 -
include/asm-generic/rwsem.h
Move the rwsem_down_read_failed() function down to below the optimistic
spinning section before enabling optimistic spinning for the readers.
There is no change in code.
Signed-off-by: Waiman Long <waiman.l...@hpe.com>
---
kernel/locking/rwsem-xadd.c
reader optimistic spinning.
Patch 6 enables reader optimistic spinning in XFS for inodes that
comes from a DAX-enabled mount point on top of persistent memory as
the CPUs can do I/O directly without waiting or sleeping.
Waiman Long (6):
locking/rwsem: Stop active read lock ASAP
locking/rwsem
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