13 Jan, 2014
1 commit
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Currently all _bh_ lock functions do two preempt_count operations:
local_bh_disable();
preempt_disable();and for the unlock:
preempt_enable_no_resched();
local_bh_enable();Since its a waste of perfectly good cycles to modify the same variable
twice when you can do it in one go; use the new
__local_bh_{dis,en}able_ip() functions that allow us to provide a
preempt_count value to add/sub.So define SOFTIRQ_LOCK_OFFSET as the offset a _bh_ lock needs to
add/sub to be done in one go.As a bonus it gets rid of the preempt_enable_no_resched() usage.
This reduces a 1000 loops of:
spin_lock_bh(&bh_lock);
spin_unlock_bh(&bh_lock);from 53596 cycles to 51995 cycles. I didn't do enough measurements to
say for absolute sure that the result is significant but the the few
runs I did for each suggest it is so.Reviewed-by: Thomas Gleixner
Signed-off-by: Peter Zijlstra
Cc: jacob.jun.pan@linux.intel.com
Cc: Mike Galbraith
Cc: hpa@zytor.com
Cc: Arjan van de Ven
Cc: lenb@kernel.org
Cc: rjw@rjwysocki.net
Cc: rui.zhang@intel.com
Cc: Linus Torvalds
Cc: Andrew Morton
Link: http://lkml.kernel.org/r/20131119151338.GF3694@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar
15 Dec, 2009
3 commits
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Make the name space hierarchy of locking functions consistent:
raw_spin* -> _raw_spin* -> __raw_spin*No functional change.
Signed-off-by: Thomas Gleixner
Acked-by: Peter Zijlstra
Acked-by: Ingo Molnar -
The name space hierarchy for the internal lock functions is now a bit
backwards. raw_spin* functions map to _spin* which use __spin*, while
we would like to have _raw_spin* and __raw_spin*._raw_spin* is already used by lock debugging, so rename those funtions
to do_raw_spin* to free up the _raw_spin* name space.No functional change.
Signed-off-by: Thomas Gleixner
Acked-by: Peter Zijlstra
Acked-by: Ingo Molnar -
Move the rwlock smp api defines and functions into a separate header
file. Makes the -rt selection simpler and less intrusive.No functional change.
Signed-off-by: Thomas Gleixner
Acked-by: Peter Zijlstra
Acked-by: Ingo Molnar
