diff options
| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2011-05-12 01:08:07 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2011-05-19 23:25:29 +0200 |
| commit | 80d02085d99039b3b7f3a73c8896226b0cb1ba07 (patch) | |
| tree | c310902423ecb00effadcb59c60cbf118d4037cb /kernel/rcutree_plugin.h | |
| parent | 11c476f31a0fabc6e604da5b09a6590b57c3fb20 (diff) | |
Revert "rcu: Decrease memory-barrier usage based on semi-formal proof"
This reverts commit e59fb3120becfb36b22ddb8bd27d065d3cdca499.
This reversion was due to (extreme) boot-time slowdowns on SPARC seen by
Yinghai Lu and on x86 by Ingo
.
This is a non-trivial reversion due to intervening commits.
Conflicts:
Documentation/RCU/trace.txt
kernel/rcutree.c
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/rcutree_plugin.h')
| -rw-r--r-- | kernel/rcutree_plugin.h | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index ed339702481..3f6559a5f5c 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -1520,6 +1520,7 @@ int rcu_needs_cpu(int cpu) { int c = 0; int snap; + int snap_nmi; int thatcpu; /* Check for being in the holdoff period. */ @@ -1530,10 +1531,10 @@ int rcu_needs_cpu(int cpu) for_each_online_cpu(thatcpu) { if (thatcpu == cpu) continue; - snap = atomic_add_return(0, &per_cpu(rcu_dynticks, - thatcpu).dynticks); + snap = per_cpu(rcu_dynticks, thatcpu).dynticks; + snap_nmi = per_cpu(rcu_dynticks, thatcpu).dynticks_nmi; smp_mb(); /* Order sampling of snap with end of grace period. */ - if ((snap & 0x1) != 0) { + if (((snap & 0x1) != 0) || ((snap_nmi & 0x1) != 0)) { per_cpu(rcu_dyntick_drain, cpu) = 0; per_cpu(rcu_dyntick_holdoff, cpu) = jiffies - 1; return rcu_needs_cpu_quick_check(cpu); |