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perf_counter: powerpc: Enable use of software counters on 32-bit powerpc

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This enables the perf_counter subsystem on 32-bit powerpc.  Since we
don't have any support for hardware counters on 32-bit powerpc yet,
only software counters can be used.

Besides selecting HAVE_PERF_COUNTERS for 32-bit powerpc as well as
64-bit, the main thing this does is add an implementation of
set_perf_counter_pending().  This needs to arrange for
perf_counter_do_pending() to be called when interrupts are enabled.
Rather than add code to local_irq_restore as 64-bit does, the 32-bit
set_perf_counter_pending() generates an interrupt by setting the
decrementer to 1 so that a decrementer interrupt will become pending
in 1 or 2 timebase ticks (if a decrementer interrupt isn't already
pending).  When interrupts are enabled, timer_interrupt() will be
called, and some new code in there calls perf_counter_do_pending().
We use a per-cpu array of flags to indicate whether we need to call
perf_counter_do_pending() or not.

This introduces a couple of new Kconfig symbols: PPC_HAVE_PMU_SUPPORT,
which is selected by processor families for which we have hardware PMU
support (currently only PPC64), and PPC_PERF_CTRS, which enables the
powerpc-specific perf_counter back-end.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: linuxppc-dev@ozlabs.org
Cc: benh@kernel.crashing.org
LKML-Reference: <19000.55404.103840.393470@cargo.ozlabs.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Paul Mackerras
2009-06-17 21:50:04 +10:00
committed by Ingo Molnar
parent a73c7d84a1
commit 105988c015
6 changed files with 51 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
arch/powerpc/kernel/Makefile
View File

@@ -95,9 +95,9 @@ obj64-$(CONFIG_AUDIT) += compat_audit.o
obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o
obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o
obj-$(CONFIG_PERF_COUNTERS) += perf_counter.o power4-pmu.o ppc970-pmu.o \
power5-pmu.o power5+-pmu.o power6-pmu.o \
power7-pmu.o
obj-$(CONFIG_PPC_PERF_CTRS) += perf_counter.o
obj64-$(CONFIG_PPC_PERF_CTRS) += power4-pmu.o ppc970-pmu.o power5-pmu.o \
power5+-pmu.o power6-pmu.o power7-pmu.o
obj-$(CONFIG_8XX_MINIMAL_FPEMU) += softemu8xx.o

25
arch/powerpc/kernel/time.c
View File

@@ -53,6 +53,7 @@
#include <linux/posix-timers.h>
#include <linux/irq.h>
#include <linux/delay.h>
#include <linux/perf_counter.h>
#include <asm/io.h>
#include <asm/processor.h>
@@ -525,6 +526,26 @@ void __init iSeries_time_init_early(void)
}
#endif /* CONFIG_PPC_ISERIES */
#if defined(CONFIG_PERF_COUNTERS) && defined(CONFIG_PPC32)
DEFINE_PER_CPU(u8, perf_counter_pending);
void set_perf_counter_pending(void)
{
get_cpu_var(perf_counter_pending) = 1;
set_dec(1);
put_cpu_var(perf_counter_pending);
}
#define test_perf_counter_pending() __get_cpu_var(perf_counter_pending)
#define clear_perf_counter_pending() __get_cpu_var(perf_counter_pending) = 0
#else /* CONFIG_PERF_COUNTERS && CONFIG_PPC32 */
#define test_perf_counter_pending() 0
#define clear_perf_counter_pending()
#endif /* CONFIG_PERF_COUNTERS && CONFIG_PPC32 */
/*
* For iSeries shared processors, we have to let the hypervisor
* set the hardware decrementer. We set a virtual decrementer
@@ -551,6 +572,10 @@ void timer_interrupt(struct pt_regs * regs)
set_dec(DECREMENTER_MAX);
#ifdef CONFIG_PPC32
if (test_perf_counter_pending()) {
clear_perf_counter_pending();
perf_counter_do_pending();
}
if (atomic_read(&ppc_n_lost_interrupts) != 0)
do_IRQ(regs);
#endif