Merge branch 'writeback' of git://git.kernel.dk/linux-2.6-block

[~andy/linux] / init / Kconfig

diff --git a/init/Kconfig b/init/Kconfig
index cb2c092702260def4bd2dfe8a2bb4334ea57fbb2..8e8b76d8a2726ba22c748b37a9c2ab5c96805f58 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -316,38 +316,28 @@ choice
        prompt "RCU Implementation"
        default TREE_RCU
 
-config CLASSIC_RCU
-       bool "Classic RCU"
-       help
-         This option selects the classic RCU implementation that is
-         designed for best read-side performance on non-realtime
-         systems.
-
-         Select this option if you are unsure.
-
 config TREE_RCU
        bool "Tree-based hierarchical RCU"
        help
          This option selects the RCU implementation that is
          designed for very large SMP system with hundreds or
-         thousands of CPUs.
+         thousands of CPUs.  It also scales down nicely to
+         smaller systems.
 
-config PREEMPT_RCU
-       bool "Preemptible RCU"
+config TREE_PREEMPT_RCU
+       bool "Preemptable tree-based hierarchical RCU"
        depends on PREEMPT
        help
-         This option reduces the latency of the kernel by making certain
-         RCU sections preemptible. Normally RCU code is non-preemptible, if
-         this option is selected then read-only RCU sections become
-         preemptible. This helps latency, but may expose bugs due to
-         now-naive assumptions about each RCU read-side critical section
-         remaining on a given CPU through its execution.
+         This option selects the RCU implementation that is
+         designed for very large SMP systems with hundreds or
+         thousands of CPUs, but for which real-time response
+         is also required.
 
 endchoice
 
 config RCU_TRACE
        bool "Enable tracing for RCU"
-       depends on TREE_RCU || PREEMPT_RCU
+       depends on TREE_RCU || TREE_PREEMPT_RCU
        help
          This option provides tracing in RCU which presents stats
          in debugfs for debugging RCU implementation.
@@ -359,7 +349,7 @@ config RCU_FANOUT
        int "Tree-based hierarchical RCU fanout value"
        range 2 64 if 64BIT
        range 2 32 if !64BIT
-       depends on TREE_RCU
+       depends on TREE_RCU || TREE_PREEMPT_RCU
        default 64 if 64BIT
        default 32 if !64BIT
        help
@@ -374,7 +364,7 @@ config RCU_FANOUT
 
 config RCU_FANOUT_EXACT
        bool "Disable tree-based hierarchical RCU auto-balancing"
-       depends on TREE_RCU
+       depends on TREE_RCU || TREE_PREEMPT_RCU
        default n
        help
          This option forces use of the exact RCU_FANOUT value specified,
@@ -387,18 +377,12 @@ config RCU_FANOUT_EXACT
          Say N if unsure.
 
 config TREE_RCU_TRACE
-       def_bool RCU_TRACE && TREE_RCU
+       def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
        select DEBUG_FS
        help
-         This option provides tracing for the TREE_RCU implementation,
-         permitting Makefile to trivially select kernel/rcutree_trace.c.
-
-config PREEMPT_RCU_TRACE
-       def_bool RCU_TRACE && PREEMPT_RCU
-       select DEBUG_FS
-       help
-         This option provides tracing for the PREEMPT_RCU implementation,
-         permitting Makefile to trivially select kernel/rcupreempt_trace.c.
+         This option provides tracing for the TREE_RCU and
+         TREE_PREEMPT_RCU implementations, permitting Makefile to
+         trivially select kernel/rcutree_trace.c.
 
 endmenu # "RCU Subsystem"
 
@@ -940,6 +924,7 @@ menu "Performance Counters"
 
 config PERF_COUNTERS
        bool "Kernel Performance Counters"
+       default y if PROFILING
        depends on HAVE_PERF_COUNTERS
        select ANON_INODES
        help
@@ -961,9 +946,17 @@ config PERF_COUNTERS
          Say Y if unsure.
 
 config EVENT_PROFILE
-       bool "Tracepoint profile sources"
+       bool "Tracepoint profiling sources"
        depends on PERF_COUNTERS && EVENT_TRACING
        default y
+       help
+        Allow the use of tracepoints as software performance counters.
+
+        When this is enabled, you can create perf counters based on
+        tracepoints using PERF_TYPE_TRACEPOINT and the tracepoint ID
+        found in debugfs://tracing/events/*/*/id. (The -e/--events
+        option to the perf tool can parse and interpret symbolic
+        tracepoints, in the subsystem:tracepoint_name format.)
 
 endmenu