summaryrefslogtreecommitdiffstats
path: root/net
diff options
context:
space:
mode:
authorTejun Heo <tj@kernel.org>2013-06-17 01:12:26 +0200
committerTejun Heo <tj@kernel.org>2013-06-17 01:12:26 +0200
commita4244454df1296e90cc961c1b636b1176ef0d9a0 (patch)
tree9be151f1e7a791dbf2d146fc5283ed246562d7f1 /net
parentpercpu-refcount: implement percpu_tryget() along with percpu_ref_kill_and_con... (diff)
downloadlinux-a4244454df1296e90cc961c1b636b1176ef0d9a0.tar.xz
linux-a4244454df1296e90cc961c1b636b1176ef0d9a0.zip
percpu-refcount: use RCU-sched insted of normal RCU
percpu-refcount was incorrectly using preempt_disable/enable() for RCU critical sections against call_rcu(). 6a24474da8 ("percpu-refcount: consistently use plain (non-sched) RCU") fixed it by converting the preepmtion operations with rcu_read_[un]lock() citing that there isn't any advantage in using sched-RCU over using the usual one; however, rcu_read_[un]lock() for the preemptible RCU implementation - CONFIG_TREE_PREEMPT_RCU, chosen when CONFIG_PREEMPT - are slightly more expensive than preempt_disable/enable(). In a contrived microbench which repeats the followings, - percpu_ref_get() - copy 32 bytes of data into percpu buffer - percpu_put_get() - copy 32 bytes of data into percpu buffer rcu_read_[un]lock() used in percpu_ref_get/put() makes it go slower by about 15% when compared to using sched-RCU. As the RCU critical sections are extremely short, using sched-RCU shouldn't have any latency implications. Convert to RCU-sched. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Kent Overstreet <koverstreet@google.com> Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'net')
0 files changed, 0 insertions, 0 deletions