| Message ID | 1331027858-7648-2-git-send-email-laijs@cn.fujitsu.com |
|---|---|
| State | New |
| Headers | show |
On Tue, Mar 06, 2012 at 05:57:34PM +0800, Lai Jiangshan wrote: > srcu_readers_active() is called without the mutex, but it touch the snap. > also achieve better cache locality a little > > Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Queued with updated commit-log message, thank you! Thanx, Paul Expand the calls to srcu_readers_active_idx() from srcu_readers_active() inline. This change improves cache locality by interating over the CPUs once rather than twice. > --- > kernel/srcu.c | 9 ++++++++- > 1 files changed, 8 insertions(+), 1 deletions(-) > > diff --git a/kernel/srcu.c b/kernel/srcu.c > index b6b9ea2..fbe2d5f 100644 > --- a/kernel/srcu.c > +++ b/kernel/srcu.c > @@ -181,7 +181,14 @@ static bool srcu_readers_active_idx_check(struct srcu_struct *sp, int idx) > */ > static int srcu_readers_active(struct srcu_struct *sp) > { > - return srcu_readers_active_idx(sp, 0) + srcu_readers_active_idx(sp, 1); > + int cpu; > + unsigned long sum = 0; > + > + for_each_possible_cpu(cpu) { > + sum += ACCESS_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[0]); > + sum += ACCESS_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[1]); > + } > + return sum & SRCU_REF_MASK; > } > > /** > -- > 1.7.4.4 >
diff --git a/kernel/srcu.c b/kernel/srcu.c index b6b9ea2..fbe2d5f 100644 --- a/kernel/srcu.c +++ b/kernel/srcu.c @@ -181,7 +181,14 @@ static bool srcu_readers_active_idx_check(struct srcu_struct *sp, int idx) */ static int srcu_readers_active(struct srcu_struct *sp) { - return srcu_readers_active_idx(sp, 0) + srcu_readers_active_idx(sp, 1); + int cpu; + unsigned long sum = 0; + + for_each_possible_cpu(cpu) { + sum += ACCESS_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[0]); + sum += ACCESS_ONCE(per_cpu_ptr(sp->per_cpu_ref, cpu)->c[1]); + } + return sum & SRCU_REF_MASK; } /**
srcu_readers_active() is called without the mutex, but it touch the snap. also achieve better cache locality a little Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> --- kernel/srcu.c | 9 ++++++++- 1 files changed, 8 insertions(+), 1 deletions(-)