perf: Tidy up after the big rename

 - provide compatibility Kconfig entry for existing PERF_COUNTERS .config's

 - provide courtesy copy of old perf_counter.h, for user-space projects

 - small indentation fixups

 - fix up MAINTAINERS

 - fix small x86 printout fallout

 - fix up small PowerPC comment fallout (use 'counter' as in register)
Reviewed-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

MAINTAINERS

@@ -4000,7 +4000,7 @@ S:	Maintained
 F:	include/linux/delayacct.h
 F:	kernel/delayacct.c
 
-PERFORMANCE COUNTER SUBSYSTEM
+PERFORMANCE EVENTS SUBSYSTEM
 M:	Peter Zijlstra <a.p.zijlstra@chello.nl>
 M:	Paul Mackerras <paulus@samba.org>
 M:	Ingo Molnar <mingo@elte.hu>

arch/powerpc/kernel/perf_event.c

@@ -41,7 +41,7 @@ DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events);
 struct power_pmu *ppmu;
 
 /*
- * Normally, to ignore kernel events we set the FCS (freeze events
+ * Normally, to ignore kernel events we set the FCS (freeze counters
  * in supervisor mode) bit in MMCR0, but if the kernel runs with the
  * hypervisor bit set in the MSR, or if we are running on a processor
  * where the hypervisor bit is forced to 1 (as on Apple G5 processors),
@@ -159,7 +159,7 @@ void perf_event_print_debug(void)
 }
 
 /*
- * Read one performance monitor event (PMC).
+ * Read one performance monitor counter (PMC).
  */
 static unsigned long read_pmc(int idx)
 {
@@ -409,7 +409,7 @@ static void power_pmu_read(struct perf_event *event)
 		val = read_pmc(event->hw.idx);
 	} while (atomic64_cmpxchg(&event->hw.prev_count, prev, val) != prev);
 
-	/* The events are only 32 bits wide */
+	/* The counters are only 32 bits wide */
 	delta = (val - prev) & 0xfffffffful;
 	atomic64_add(delta, &event->count);
 	atomic64_sub(delta, &event->hw.period_left);
@@ -543,7 +543,7 @@ void hw_perf_disable(void)
 		}
 
 		/*
-		 * Set the 'freeze events' bit.
+		 * Set the 'freeze counters' bit.
 		 * The barrier is to make sure the mtspr has been
 		 * executed and the PMU has frozen the events
 		 * before we return.
@@ -1124,7 +1124,7 @@ const struct pmu *hw_perf_event_init(struct perf_event *event)
 }
 
 /*
- * A event has overflowed; update its count and record
+ * A counter has overflowed; update its count and record
  * things if requested.  Note that interrupts are hard-disabled
  * here so there is no possibility of being interrupted.
  */
@@ -1271,7 +1271,7 @@ static void perf_event_interrupt(struct pt_regs *regs)
 
 	/*
 	 * Reset MMCR0 to its normal value.  This will set PMXE and
-	 * clear FC (freeze events) and PMAO (perf mon alert occurred)
+	 * clear FC (freeze counters) and PMAO (perf mon alert occurred)
 	 * and thus allow interrupts to occur again.
 	 * XXX might want to use MSR.PM to keep the events frozen until
 	 * we get back out of this interrupt.

arch/x86/kernel/cpu/perf_event.c

@@ -2083,7 +2083,7 @@ void __init init_hw_perf_events(void)
 
 	pr_info("... version:                %d\n",     x86_pmu.version);
 	pr_info("... bit width:              %d\n",     x86_pmu.event_bits);
-	pr_info("... generic events:        %d\n",     x86_pmu.num_events);
+	pr_info("... generic registers:      %d\n",     x86_pmu.num_events);
 	pr_info("... value mask:             %016Lx\n", x86_pmu.event_mask);
 	pr_info("... max period:             %016Lx\n", x86_pmu.max_period);
 	pr_info("... fixed-purpose events:   %d\n",     x86_pmu.num_events_fixed);

include/linux/perf_event.h

@@ -395,7 +395,7 @@ enum perf_event_type {
 	 *	#
 	 *	# That is, the ABI doesn't make any promises wrt to
 	 *	# the stability of its content, it may vary depending
-	 * 	# on event_id, hardware, kernel version and phase of
+	 *	# on event, hardware, kernel version and phase of
 	 *	# the moon.
 	 *	#
 	 *	# In other words, PERF_SAMPLE_RAW contents are not an ABI.

init/Kconfig

@@ -920,26 +920,31 @@ config HAVE_PERF_EVENTS
 	help
 	  See tools/perf/design.txt for details.
 
-menu "Performance Counters"
+menu "Kernel Performance Events And Counters"
 
 config PERF_EVENTS
-	bool "Kernel Performance Counters"
-	default y if PROFILING
+	bool "Kernel performance events and counters"
+	default y if (PROFILING || PERF_COUNTERS)
 	depends on HAVE_PERF_EVENTS
 	select ANON_INODES
 	help
-	  Enable kernel support for performance counter hardware.
+	  Enable kernel support for various performance events provided
+	  by software and hardware.
 
-	  Performance counters are special hardware registers available
-	  on most modern CPUs. These registers count the number of certain
+	  Software events are supported either build-in or via the
+	  use of generic tracepoints.
+
+	  Most modern CPUs support performance events via performance
+	  counter registers. These registers count the number of certain
 	  types of hw events: such as instructions executed, cachemisses
 	  suffered, or branches mis-predicted - without slowing down the
 	  kernel or applications. These registers can also trigger interrupts
 	  when a threshold number of events have passed - and can thus be
 	  used to profile the code that runs on that CPU.
 
-	  The Linux Performance Counter subsystem provides an abstraction of
-	  these hardware capabilities, available via a system call. It
+	  The Linux Performance Event subsystem provides an abstraction of
+	  these software and hardware cevent apabilities, available via a
+	  system call and used by the "perf" utility in tools/perf/. It
 	  provides per task and per CPU counters, and it provides event
 	  capabilities on top of those.
 
@@ -950,14 +955,26 @@ config EVENT_PROFILE
 	depends on PERF_EVENTS && EVENT_TRACING
 	default y
 	help
-	 Allow the use of tracepoints as software performance counters.
+	 Allow the use of tracepoints as software performance events.
 
-	 When this is enabled, you can create perf counters based on
+	 When this is enabled, you can create perf events 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.)
 
+config PERF_COUNTERS
+	bool "Kernel performance counters (old config option)"
+	depends on HAVE_PERF_EVENTS
+	help
+	  This config has been obsoleted by the PERF_EVENTS
+	  config option - please see that one for details.
+
+	  It has no effect on the kernel whether you enable
+	  it or not, it is a compatibility placeholder.
+
+	  Say N if unsure.
+
 endmenu
 
 config VM_EVENT_COUNTERS

kernel/perf_event.c

 /*
- * Performance event core code
+ * Performance events core code:
  *
  *  Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
  *  Copyright (C) 2008-2009 Red Hat, Inc., Ingo Molnar