Messages in this thread Patch in this message | | | Subject | [PATCH] RCU: remove alignment padding from rcu_data on 64 bit builds | From | Richard Kennedy <> | Date | Thu, 05 May 2011 16:50:04 +0100 |
| |
Reorder rcu_data to remove 8 bytes of alignment padding on 64 bit builds so saving a total of 16 bytes per cpu, (rcu_sched_data & rcu_bh_data).
When CONFIG_NO_HZ is set, it shrinks the size of this structure from 264 to 256 bytes allowing it to fit into one fewer cache lines.
Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk> ---
patch against v2.6.39-rc6 compiled & tested on x86_64
I've been running with this patch for some weeks and have not seen any issues.
regards Richard
diff --git a/kernel/rcutree.h b/kernel/rcutree.h index e8f057e..fcced0f 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -176,6 +176,9 @@ struct rcu_data { bool qs_pending; /* Core waits for quiesc state. */ bool beenonline; /* CPU online at least once. */ bool preemptable; /* Preemptable RCU? */ + + int cpu; + struct rcu_node *mynode; /* This CPU's leaf of hierarchy */ unsigned long grpmask; /* Mask to apply to leaf qsmask. */ @@ -238,8 +241,6 @@ struct rcu_data { unsigned long n_rp_gp_started; unsigned long n_rp_need_fqs; unsigned long n_rp_need_nothing; - - int cpu; }; /* Values for signaled field in struct rcu_state. */
| |